UNIVERSITÀ DEL SALENTO
Dipartimento di Ingegneria dell’Innovazione
Dipartimento di Scienza dei Materiali
Società Chimica Italiana
Divisione di Chimica Fisica
Gallipoli, 17-22 Giugno 2007
Con il patrocinio di
Provincia di Lecce
Comune di Gallipoli
Si ringraziano gli Sponsor:
Costruzioni Solari S.r.l., Zona
P.I.P.-73020 Cavallino (Lecce),
Italy
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Comitato Scientifico
Vincenzo Barone
Angela Agostiano
Piero Baglioni
Stefania Milioto
Nicolae Viorel Pavel
Vincenzo Schettino
Mariano Venanzi
Ludovico Valli
Comitato Organizzatore
Ugo Lamanna
Angela Agostiano
Serena Casilli
Lucia Catucci
Fulvio Ciriaco
Pinalysa Cosma
Lucia Curri
Luigi Dimo
Ameriga Fanigliulo
Paola Fini
Alessandra Genga
Gabriele Giancane
Livia Giotta
Disma Mastrogiacomo
Francesco Milano
Massimo Trotta
Ludovico Valli
Segreteria Organizzativa
Luigi Dimo
Gabriele Giancane
Serena Casilli
Natalia Guerra Carbajo
Dipartimento di Ingegneria dell’Innovazione
Università del Salento
Via Monteroni
73100 Lecce
Tel. 0832 297374/ 325
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PROGRAMMA DEL CONGRESSO
4
Domenica 17 Giugno
16.00 – 20.00
Registrazione Delegati
20.30 – on
Welcome Reception
Lunedì 18 Giugno
8.45 – 9.15
9.15 – 10.00
10.00 - 10.20
10.20 – 10.40
10.40 – 11.00
Inaugurazione lavori
Relazione Plenaria Prof. P. Rich (University College, London):
New methods to study protein chemistry with ATR infrared
spectroscopy
Bocchinfuso Gianfranco (Università di Roma “Tor Vergata”):
A polysaccharide forming nanochannels in the hydrogel phase:
study of static and dynamic effects induced by a soft-confinement
Cannistraro Salvatore (Università della Tuscia):
Yeast Cytochrome c molecules immobilized on carbon nanotubes:
A Conductive Atomic Force Microscopy characterization at the
single molecule level
Carlotti Benedetta (Università di Perugia):
AFM force curve investigation of DNA elasticity
11.00 – 11.30
11.30 – 11.50
11.50 – 12.10
12.10 - 12.30
12.30 – 12.50
12.50 – 13.10
Coffee Break
Mavelli Fabio (Università di Bari):
Stochastic simulations of proto-cell dynamics
Moncelli Maria Rosa (Università di Firenze):
ATPasi di tipo P in modelli di membrane biologiche: studio delle
proprietà funzionali
Satriano Cristina (Università di Catania):
Physico-chemical aspects of peptide adsorption onto hydrophilic
and hydrophobic substrates
Scipioni Anita (Università di Roma “La Sapienza”):
Structural analysis of 30 nm chromatin fiber architecture
Narducci Dario (Università di Milano Bicocca):
Bioinspired Chemical Sensing: Molecular Recognition of Gaseous
Species at Nanostructured Surfaces
15.00 – 17.00
Sessione Poster
17.00 – 17.30
Coffee Break
17.30 – 18.45
Rassegna critica di Poster sezione “Chimica Fisica dei Materiali”
Breve presentazione di poster selezionati
5
Martedì 19 Giugno
9.00 – 9.45
9.45 - 10.05
10.05 – 10.25
10.25 – 10.45
Relazione Plenaria Prof. M. Becucci (Università di Firenze):
Struttura e reattività di molecole isolate e clusters
Cimino Paola (Università di Salerno):
Calculation of EPR parameters in solution by a recent integrated
computational approach
De Filpo Giovanni (Università della Calabria):
Flexible nano-photo-electrochromic film
Ferrante Camilla (Università di Padova):
Role of excitonic interactions on the nonlinear absorption spectra
of porphyrin J-aggregates
10.45 – 11.15
11.15 – 11.35
11.35 – 11.55
11.55 - 12.15
12.15 – 12.35
Coffee Break
Melandri Sonia (Università di Bologna):
Importance of the hydrogen bond in tautomeric equilibria and in
molecular complex formation. Rotational spectroscopy in
supersonic expansions
Morresi Assunta (Università di Perugia):
Trehalose and glucose dynamics by low-frequency scattering
techniques
Selli Elena (Università di Milano):
Photocatalytic activity of surface fluorinated and/or Au-modified
titanium dioxide
Scaranto Jessica (Università di Venezia):
Study on the adsorbate-substrate interaction between
halogenated ethenes and TiO2: IR spectroscopy and quantummechanical calculations
15.00 – 16.00
Sessione Poster
16.00 – 17.15
Rassegna critica di Poster per la sezione “Colloidi ed Interfasi”
Breve presentazione di poster selezionati
17.15 – 17.45
Coffee Break
17.45 – 19.00
Rassegna critica di Poster per la sezione “Spettroscopia e
Fotochimica”
Breve presentazione di poster selezionati
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Mercoledì 20 Giugno
9.00 – 9.45
9.45 - 10.05
10.05 – 10.25
10.25 – 10.45
Relazione Plenaria Prof. G. Ruocco (Università di Roma “La
Sapienza”):
Aging and flow in a colloidal suspension
Caminati Gabriella (Università di Firenze):
Addressable DNA architectures anchored to Supported Lipid
Bilayers
Caracciolo Giulio (Università di Roma “La Sapienza”):
Structural Stability Against Disintegration by Anionic Lipids
Rationalizes the Efficiency of Cationic Liposome/DNA Complexes
Lazzara Giuseppe (Università di Palermo):
Aggregation of triblock copolymers in water induced by
chlorinated oils
10.45 – 11.15
11.15 – 11.35
11.35 – 11.55
11.55 - 12.15
12.15 – 12.35
15.00 – 16.15
Coffee Break
Marini Alberto (Scuola Normale Superiore di Pisa):
Orientational order properties of nematic and smectic B phases of
fluorinated liquid crystals by means of 13C NMR, optical and
dielectric studies
Peddis Davide (Università di Cagliari):
Magnetic properties of ultra-small nanoparticles: beyond the
influence of particles size
Ricchiardi Gabriele (Università di Torino):
Computational and spectroscopic screening of microporous
materials for molecular hydrogen storage
Striccoli Marinella (CNR-IPCF, Bari):
Luminescent Nanocrystals in PMMA Based Co-polymers: Novel
Nanocomposite Materials for Nano Imprint Lithography
Rassegna critica di Poster per la sezione “Chimica Fisica Biologica
ed Ambientale”
Breve presentazione di poster selezionati
17.00
Gita e Cena Sociale
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Giovedì 21 Giugno
9.00 – 9.45
9.45 – 10.05
10.05 – 10.25
10.25 – 10.45
Relazione Plenaria Prof. D. M. Guldi (Università di Erlangen):
Carbon Based Electron Donor Acceptor Hybrids for Solar
Energy Conversion
Bee Antonio (Costruzioni Solari):
Stato dell’Arte e Potenzialità del Solare Termico
Binetti Simona (Università di Milano “Bicocca”
Role of defects and defect interactions on the photovoltaic
properties of solar grade silicon)
Torsi Luisa (Università di Bari):
Chiral recognition with enhanced sensing organic thin-film
transistors
10.45 – 11.15
11.15 – 11.35
11.35 – 11.55
11.55 - 12.15
12.15 – 12.35
12.35 – 12.55
15.00 – 16.15
Coffee Break
Bisio Chiara (Università del Piemonte Orientale):
Structural and physico-chemical studies of innovative layered Almodified magadiite materials
Latterini Loredana (Università di Perugia):
Preparation and optical properties of metal nanostructures
Manzoli Maela (Università di Torino):
Characterisation of highly dispersed gold on ZrO2 catalysts active
in the WGS reaction
Massarotti Vincenzo (Università di Pavia):
Sostituzione cationica e proprietà in “bronzi di tungsteno”
Bystrenova Eva (ISMN-CNR Bologna):
Growth of neural cells on ultra thin organic semiconductors
Rassegna critica di Poster per la sezione “Chimica Fisica Teorica e
Computazionale”
Breve presentazione di poster selezionati
16.15 – 16.45
Coffee Break
16.45 – 18.15
Tavola Rotonda
18.15 – 19.45
Assemblea Divisione
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Venerdì 22 Giugno
9.00 – 9.45
9.45 - 10.05
10.05 – 10.25
10.25 – 10.45
Relazione Plenaria Prof.ssa N. Rega (Università di Napoli):
Ab-initio molecular dynamics of solute-solvent systems
based on non periodic boundary conditions: applications to
spectroscopic properties
Tabacchi Gloria (Universita' degli Studi dell'Insubria):
On the active role of substrate reactivity in the context of
enzymatic dehydrogenations: a theoretical investigation
Puzzarini Cristina (Università di Bologna):
Vibrational Corrections to Dipolar Coupling Constants: an
Alternative for Determining Equilibrium Distances from
Rotational Spectroscopy
Di Pietro Elisa (Università di Firenze):
Reazione di idrolisi della molecola di diborano in soluzione
tramite simulazioni di dinamica molecolare ab initio
10.45 – 11.15
11.15 – 11.35
11.35 – 11.55
11.55 - 12.15
12.15 – 12.35
12.35 – 12.55
12.55 – 13.15
Coffee Break
Monaco Guglielmo (Università di Salerno):
From paratropic ring currents to closed-shell molecular magnets
Pavone Michele (Università di Napoli “Federico II”):
DFT-D study of the benzene dimer: structural minima, energies
and molecular dynamics
Santoro Fabrizio (IPCF – CNR, Pisa):
Dynamics of the Photodeactivation processes in DNA nucleobases
Manca Gabriele (Università di Pisa):
A combined approach of theory and experiment for the study of
platinum clusters derivatives
Pedone Alfonso (Università di Modena e Reggio Emilia)
Insight into Elastic Properties of binary alkali silicate glasses:
prediction and Interpretation through atomistic simulation
techniques
Cerimonia di chiusura
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ELENCO POSTER DELLA SEZIONE
CHIMICA FISICA BIOLOGICA ED AMBIENTALE
P1.1 Nuclear Magnetic Resonance of
129
Xe and 1H: structural characterization of hydrophobic cavities of
Myoglobins.
Roberto Anedda, Benedetta Era, Antonella Fais, Matteo Ceccarelli, Marcella Corda, Mariano Casu and Paolo
Ruggerone
P1.2 Application of ISORROPIA and SOAP modules within CAMx model for PM simulation.
Elena Chianese, Guido Barone, Angelo Riccio
P1.3 An Application of OSAT Probing Tool in Southern Italy.
Elena Chianese, Alessia Riccio, Guido Barone, Angelo Riccio
P1.4
PM Indoor Pollution Reduction by TiO2 Films.
Elena Chianese, Giuseppina Pironti, Guido Barone, Angelo Riccio
P1.5 Il metano ed il futuro del clima.
Elena Chianese, Guido Barone, Angelo Riccio
P1.6 Conformational stability of a thermostable phosphotriesterase from the archaeon Sulfolobus
solfataricus (SsoPox)
P. Del Vecchio, P. Carullo, G. Barone, L. Merone, M. Rossi, G. Manco
P1.7 Mn2+ in marmi bianchi antichi. Determinazione della cava con spettroscopia EPR tramite
parametri magnetici
Alfonso Zoleo and Marina Brustolon
P1.8 Osservazione diretta dell’effetto dell’associazione con la base complementare sul potenziale di
ossidazione di guanosina e adenosina
Amedeo Capobianco, Tonino Caruso, Andrea Peluso
P1.9 Spectroscopic study of ochratoxin A and its interaction with cyclodextrins
R. Verrone, L. Catucci, P. Fini, P. Cosma, A. Agostiano, V. Lippolis, M. Pascale
P1.10 Activity of photosynthetic membrane proteins of Rhodobacter sphaeroides: a possible role of
cardiolipin
Vincenzo De Leo, Lucia Catucci, Francesco Milano, Angela Corcelli, Angela Agostiano
P1.11 Photosystem II thermal stability and pigment photobleaching: Effect of membrane lipids
Andrea Ventrella, Lucia Catucci, Giuseppe Mascolo, Angela Corcelli, Angela Agostano
P1.12 Studio sul metabolismo dell’arsenico attraverso spettroscopia NMR in vivo.
Marianna Aggravi, Claudia Bonechi, Claudio Rossi, Nadia Marchettini, Enzo Tiezzi, Alessandro Donati
P1.13 Investigation of Self-Assembling Ionic Peptides
M. Alderighi, C. Duce, S. Monti, R. Solaro, M.R. Tiné
P1.14 Use of Cyclodextrins to Improve the Photostability of RB in Aqueous Solutions
P. Fini, A.E. Di Mauro, S. Rochira, P. Cosma, L. Catucci, M. Castagnolo, A. Agostiano
P1.15 Studio del meccanismo di degrado di vetri antichi rinvenuti nel parco archeologico di Siponto
(Foggia)
A. Genga, M. Siciliano, L. Famà, D. Manno, T. Siciliano, A. Mangone, A. Traini, C. Laganara
P1.16 Uno studio combinato spettroscopico-teorico della struttura dell'ottasilicato di sodio RUB18
M. F. Iozzi, M. Cossi, C. Bisio, T. R. Macedo, L. Marchese
P1.17 Influence Of Crowded/Confined Environments On Dynamics Of Amyloidogenic Protein SelfAssenbling
A. N. Lazar, E Bystrenova, C. Dionigi, P. Greco, S. Dutta, P. Stoliar, M.G. Cacace and F. Biscarini
P1.18 Studio strutturale del processo di “unfolding” dell’albumina umana
Claudia Leggio, Luciano Galantini, Nicolae Viorel Pavel
P1.19 Stabilità termodinamica del multimero del telomero umano ed energetica dell’interazione con la
porfirina cationica
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Luigi Petraccone, Luigi Martino, Bruno Pagano, Guido Barone, Concetta Giancola
P1.20 ATPasi di tipo P in modelli di membrane biologiche: studio delle proprietà funzionali
M.R. Moncelli, G. Bartolommei, F. Tadini-Buoninsegni
P1.21 Direct micelles as microreactors for the tuning of cobalt ferrite nanoparticle sizes
A. Ardu, C. Cannas, A. Musinu, D. Peddis, G.Piccaluga, D. Gatteschi, C. Sangregorio
P1.22 Analisi termodinamica dell’interazione tra ligandi e quadruple eliche del DNA telomerico umano
Bruno Pagano, Antonio Randazzo, Gary N. Parkinson, Carlo A. Mattia, Concetta Giancola
P1.23 Sintesi stereoselettiva di 1,2,3-triaril aziridine e risoluzione strutturale via H1-NMR di derivati con
Pt(II)
E. Pindinelli, M. Fabio, L. Troisi
P1.24 Evidence for different routes of oxidation in the laccase-mediator system: a multifrequency EPR
and DFT study.
R. Pogni, B. Brogioni, A. Sinicropi, M. C. Baratto, P. Giardina, G. Sannia, R. Basosi
P1.25 Membrane insertion and bilayer perturbation by antimicrobial peptide
Sara Pistolesi, Jimmy B. Feix, Rebecca Pogni
P1.26 The Fluorescence of Tryptophan in Monellin and Parvalbumin Resolved at the ab initio
Multiconfigurational Perturbation Theory Level
Adalgisa Sinicropi, Sara Pistolesi, Rebecca Pogni, Riccardo Basosi, Massimo Olivucci
P1.27 Monitoring of the aggregation behaviour of a catalytic protein targeted by anticancer drugs
through analysis of its intrinsic fluorescence
Stefania Ferrari, Maria Paola Costi, Monica Caselli, Glauco Ponterini
P1.28 Multicomponent cationic liposome/DNA complexes: efficient vectors for gene delivery
G. Caracciolo, D. Pozzi, R. Caminiti, C. Marchini, M. Montani, A. Amici, H. Amenitsch
P1.29 Aspetti dinamici su scala macroscpopica derivanti da organizzazione mesoscopica
Grazia Biosa, Marcus Hauser, Sandra Ristori, Eugenio Simoncini, Enzo Tiezzi e Mauro Rustici
P1.30 Superstructural Organization of a G-Quadruplex Forming Homopuryne-Homopyrimidine Tract
belonging to the Human Telomerase Reverse Transcriptase (H-Tert) Gene Promoter.
Maria Savino, Sabrina Pisano, Michela Varra, Emanuela Micheli, Teresa Coppola, Luciano Mayol, Pasquale De
Santis
P1.31 Analisi Emergetica dell’impatto ambientale delle faggete cedue lombarde
Alberto Schiraldi, Thomas Epis
P1.32 Scuola Nazionale Di Metodologie Chimico Fisiche Per Lo Studio Dei Sistemi Biologici
Alberto Schiraldi
P1.33 Peptides with regular enantiomeric sequences as self-assembling nanotubes for nanotechnology.
A. Scipioni, S. Morosetti, P. De Santis
P1.34 Isotopic effect on the kinetics of the Belousov-Zhabotinsky reaction: Cerium-Malonic subsystem.
Simoncini E., Rossi F., Rustici M., Marchettini N.
P1.35 Theoretical Studies on the Structure of Polycyclic Aromatic Hydrocarbons (PAHs) and Soot
Platelets and Their Oxidative Functionalization
Anna Giordana, Andrea Maranzana, Giovanni Ghigo, Mauro Causà, G. Tonachini
P1.36 Vapor pressures, sublimation and vaporization enthalpies using isothermal and non-isothermal
thermogravimetry
S. Vecchio
P1.37 Vaporization study of acetaminophen and three of its derivatives using isothermal and nonisothermal thermogravimetry
V. Rossi, M. Tomassetti, S. Vecchio
P1.38 Monitoring peptide folding by Time-Resolved Spectroscopies: the effect of a single Gly to Aib
susbtitution
Mariano Venanzi, Emanuela Gatto, Gianfranco Bocchinfuso, Antonio Palleschi, Lorenzo Stella, Chiara Baldini,
Fernando Formaggio, Claudio Toniolo, Basilio Pispisa
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P1.39 Antimicrobial peptides chelating lanthanide ions: the case of Trichogin GAIV analogs and
Terbium(III)
Mariano Venanzi, Emanuela Gatto, Lorenzo Stella, Gianfranco Bocchinfuso, Antonio Palleschi, Fernando
Formaggio, Claudio Toniolo
P1.40 Effect of aggregation and membrane-water partition on peptide antimicrobial activity: a lesson
learned from spectroscopic studies.
L. Stella, C. Mazzuca, G. Bocchinfuso, F. Formaggio, E. Gatto, K. S. Hahm, A. Palleschi, B. Pispisa, C. Toniolo, M.
Venanzi
P1.41 A novel method for detection of Se-Met inclusion into protein crystals via Raman microscopy
Alessandro Vergara, Antonello Merlino, Elio Pizzo, Giuseppe D’Alessio, Lelio Mozzarella
P1.42 Nanovoid-structured TiO2 encapsulating (I2)n molecules: a way to tune the photoactivity in the
visible region
A. Zecchina, G. Ricchiardi, S. Usseglio, A. Damin, D. Scarano, C. Lamberti, S. Bordiga
P1.43 MeCAL-2: New catalysts for methane combustion
G. A. V. Martins, G. Berlier, M. Strauss, S. Coluccia, L. Marchese, Heloise O. Pastore, A. Scarpa, R. Pirone
P1.44 Pt-Ba/Al2O3 LNT catalysts: TRM and FT-IR analysis of the reduction of stored NOx in different
model atmospheres
F. Frola, F. Prinetto, G. Ghiotti, I. Nova, L. Lietti, P. Forzatti
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ELENCO POSTER DELLA SEZIONE
SPETTROSCOPIA E FOTOCHIMICA
P2.1 Small, Infrared, Luminescent Type II Semiconductor Nanocrystals for Animal Imaging
Matteo Amelia, Loredana Latterini, Gian Gaetano Aloisi, Fausto Elisei
P2.2 Doped Nanocrystals: Coupling Optical and Magnetic Properties
Matteo Amelia, Loredana Latterini, Gian Gaetano Aloisi, Fausto Elisei
P2.3 Magnetic Resonance investigations on Cultural Heritage materials.
Alfonso Zoleo, Marco Ruzzi, Lorenzo Franco, Daria Confortin, Marina Brustolon
P2.4 The triplet of DCM observed for the first time: a TR-EPR study of the dye inclusion in a KH
Phthalate single crystal.
Marina Brustolon, Roberto Zanré, Antonio Barbon, Kristin L. Wustholz, Bart Kahr
P2.5 Laser Ablation-Inductively Coupled Plasma Mass Spectrometry For The Determination Of Heavy
Metals In Airborne Pariculate Matter (PM10)
Ameriga Fanigliulo, Giuseppe E. De Benedetto
P2.6 Spectral studies of Nicotinamide and Zinc phthalocyanine complexes
R. Del Sole, M. R. Lazzoi, A. De Luca, G. Vasapollo
P2.7 Studio degli ioni Mg2+ e Ca2+ in metanolo liquido attraverso dinamica molecolare ab initio CarParrinello
Cristian Faralli, Marco Pagliai, Gianni Cardini e Vincenzo Schettino
P2.8 Low-frequency Raman scattering from aqueous solutions of carbohydrates
S. Perticaroli, P. Sassi, A. Morresi, M. Paolantoni
P2.9 Competitive photoisomerization pathways of 1,2-diarylethenes and related compounds
G. Bartocci, S. Ciorba, G.Ginocchietti, U. Mazzucato, A. Spalletti
P2.10 FTIR spectroscopy and thermodynamics of hydrogen adsorbed in a cross-linked polymer
Olena Zavorotynska, Giuseppe Spoto, Jenny Vitillo, Alessandro Damin, Francesca Bonino, Adriano Zecchina
P2.11 Quinol re-oxidation in the Reaction Center photocycle in vitro
Nicola De Nicolò, Péter Maróti, László Nagy, Massimo Trotta, Francesco Milano, Angela Agostiano.
P2.12 Studio di processi di binding a carico di cellule batteriche mediante spettroscopia ATR-FTIR
differenziale
Livia Giotta, Disma Mastrogiacomo, Francesca Italiano, Angela Agostiano, Francesco Milano, Massimo Trotta
P2.13 Does the lipid environment influence the spectral and kinetic properties of semiquinones in
bacterial photosynthetic reaction centres?
F. Milano, E. Altamura, A. Agostiano, L. Giotta, L. Nagy, P. Maroti, M. Trotta
P2.14 The hydrophobic chain length of phospholipids influences the functioning of photosynthetic
Reaction Centres reconstituted in proteoliposomes.
M. Trotta, F. Milano, N. De Nicolò, L. Giotta, L. Nagy, P. Maroti, A. Agostiano
P2.15 New Sol-Gel Hybrid Materials for High Energy Applications in Nonlinear Optics
I.Fortunati; R.Signorini; R.Bozio; G.Brusatin; M.Guglielmi; S.Dirè
13
ELENCO POSTER DELLA SEZIONE
COLLOIDI ED INTERFASI
P3.1 Thermal Analysis Characterization of Some Cationic Liposomes
Bonicelli M. G., Giansanti L., Mancini G., Pascale F.
P3.2 Effect of dopant (Nd, Er, Eu and Ce) amount on yttrium aluminum garnet nanoparticles structure
Eugenio Caponetti, Delia Chillura Martino, Maria Luisa Saladino, Stefano Enzo, Giulio Ibba
P3.3 Studio strutturale di polimeri supramolecolari host-guest
Luciano Galantini, Claudia Leggio, Nicolae Viorel Pavel, Massimiliano Anselmi, Alfredo Di Nola, Aida Jover,
Francisco Meijide, Victor Hugo Soto Tellini, José Vázquez Tato
P3.4 Physico-Chemical and Structural Properties of hydrogels formed by Chitosan, in the Presence and
Absence of Poly(vinylpyrrolidone) and Sodium decylsulfate
Gaetano Mangiapia , Luigi Paduano, Henrich Frielinghaus, Gerardino D’Errico, Ornella Ortona, Roberto Sartorio
P3.5 Self-assembly of starch stabilized Ag nanocrystals into ribbon-like and globular agglomerate
structures for biosensors application.
A. Serra, D. Manno, E. Filippo, T. Siciliano, A. Tepore
P3.6 Kinetics of Gelation of Aqueous Laponite Dispersions in the Presence of Tri-block Copolymers and
their Homopolymers. Rheological and Dynamic Light Scattering Studies
R. De Lisi, M. Gradzielski, G. Lazzara, S. Milioto and N. Muratore
P3.7 The aggregative behavior of hydrophobically modified chitosans of 10% level substitution
Ornella Ortona, G. D’Errico, G. Mangiapia, L. Paduano
P3.8 Modeling of H2 adsorption and spectroscopic observation of the ortho-para conversion on the ETS10 titanosilicate
G. Ricchiardi, J. G. Vitillo, D. Cocina, G. Spoto, A. Zecchina
P3.9 Structure and nuclearity of active sites in Fe-zeolites: comparison with iron sites in enzymes and
homogeneous catalysts
Gabriele Ricchiardi, Mickaël Rivallan, Gloria Berlier, Carlo Lamberti, Adriano Zecchina
P3.10 FT-IR Study of the State of Iron(III) Chloride Clusters Confined in AOT Reverse Micelles
V. Turco Liveri, R. Biancheri, L. Ceraulo, S. Fanara, C. Giordano, A. Ruggirello
P3.11 Investigation of the adsorption of PEG1500-12-acyloxystearate surfactants into phospholipids
bilayers: An Ellipsometry and Cryo-TEM study.
Mauro Vaccaro, Christian von Corswant, Olle Söderman
P3.12 Characterisation of new gold catalysts supported on mixed ceria-titania oxides for the water-gas
shift and preferential CO oxidation reactions
Floriana Vindigni, Maela Manzoli, Anna Chiorino, Tatyana Tabakova, Vasko Idakiev, Flora Boccuzzi
P3.13 Gas-phase photocatalytic reduction of NOx onto immobilized colloidal TiO2 nanocrystals: a
preliminary study
P. Ielpo, G. Lasorella, R. Comparelli, A. Panniello, M. Striccoli, M. Caselli, A. Agostiano, M. L. Curri
14
ELENCO POSTER PER LA SEZIONE
CHIMICA FISICA DEI MATERIALI
P4.1 Nuclear Magnetic Resonance of 129Xe used as a probe for the characterization of void space in
crystalline microporous dipeptides: thermodynamics and molecular details of sorption.
Roberto Anedda, Dmitriy V. Soldatov, Igor L. Moudrakovski, Mariano Casu, John A. Ripmeester
P4.2 SiOx and SiNx layers with improved barrier effect and tribological properties
E. Angelini, R. d’Agostino, S. Grassini, F. Palumbo, F. Rosalbino
P4.3 Synthesis and characterization of hybrid organic/inorganic mesoporous photoactive nanoparticles
Bertolino, C.A., Caputo, G., Gianotti, E.
P4.4 Thermal Analysis Characterization of Some Processes Related to Disproportionation of Stannous
Oxide
Bonicelli M. G., Ceccaroni G., Gauzzi F, Mariano G.
P4.5 Surface Chemistry Effects on the Early Growth Stages of Pentacene Films from a Soluble
Precursor on Silicon-Based Materials
C. Musumeci, C. Cascio, A. Scandurra, G.F. Indelli, C. Bongiorno, S. Ravesi, B. Pignataro
P4.6 New advances in the high temperature decomposition of H2SO4
S. Brutti, L. Bencivenni, V. Barbarossa, G. De Maria
P4.7 Lithium Order-Disorder in Superionic LLTO: Theory and Experiment
M. Catti
P4.8 Tuning of chemical and physical properties of Poly(methyl metacrylate)- TiO2 nanocrystals based
nanocomposites for sensing applications
A. Convertino, G. Leo, M. Striccoli, M. Tamborra, C. Sciancalepore, M. L. Curri
P4.9 A computational multiscale approach to the modelling of 45S5 Bioglass®
M. Corno, A. Pedone, B. Civalleri, M.C. Menziani, P. Ugliengo
P4.10 Structural and chemical properties of the hydroxyapatite surface. A computational ab initio and a
microcalorimetric/IR spectroscopic characterization
M. Corno, L. Bertinetti, V. Bolis, C. Busco, G. Martra, P. Ugliengo
P4.11 Tailored functionalization of luminescent colloidal nanocrystals for selective 2/3D assembly
M.Corricelli, R. Comparelli, N. Depalo, M. Striccoli, V. Saadhu, J. Huskens, M.L. Curri
P4.12 Physical properties of the magnetic superconductor Ru – 1222 obtained from Ru–1212 and
Ce0.6Gd0.4O1.8 powders
G. A. Costa, C. Artini, M. M. Carnasciali, R. Masini, A. Ubaldini
P4.13 Fluorination of TiO2: effects on surface hydroxyl groups and photoreactivity
M.G. Faga, M. Minella, V. Maurino, G. Martra, C. Minero, E. Pelizzetti, S. Coluccia
P4.14 Transient Absorption properties of the monomer and dimer of TTF radical cation
Eleonora Garbin, Elisabetta Collini, Camilla Ferrante, Renato Bozio
P4.15 Squaraine dyes as powerful nonlinear absorbers in the NIR region
Elisabetta Collini, Ilaria Fortunati, Luca Ciaffoni, Camilla Ferrante, Renato Bozio, Luca Beverina, Alessandro
Abbotto, Giorgio A. Pagani
P4.16 TPA Absorption properties of octupolar metal complexes
Simone Mazzucato, Ilaria Fortunati, Sara Scolaro, Michele Zerbetto, Camilla Ferrante, Raffaella Signorini, Danilo
Pedron, Renato Bozio, Danika Locatelli, Stefania Righetto, Dominique Roberto, Renato Ugo, Alessandro Abbotto,
Graziano Archetti, Luca Beverina, Sergio Ghezzi
P4.17 Effect of Grain Size on The Magnetic Properties of La1-XCaxMnO3 Manganites Nanoparticles
C. Castellano, M.R. Cimberle, M. Ferretti, A. Martinelli, R. Masini
P4.18 A multi-frequency EPR study on TiO2 colloidal nanocrystals: a closer insight on the catalytic
activity
M. Fittipaldi, C. Sangregorio, D. Gatteschi, N. Grassi, M. L. Curri, R. Comparelli, M. Striccoli, A. Agostiano
15
P4.19 Correlation between transport properties and lattice effects in the NdCoO3 based catalysts and
sensor materials
G. Flor, C. Tealdi, L. Malavasi, F. Gozzo, G. Chiodelli
P4.20 Challenges In Biocatalysis: Immobilization Of Porcine Pepsin In Mesoporous Silicas
Haresh G. Manyar, Simonetta Tumbiolo, Enrica Gianotti, Salvatore Coluccia, Osamu Terasaki
P4.21 Luminescent nanocrystal modified epoxy photoresist for the fabrication of 3-D high aspect-ratio
microstructures
C. Ingrosso, V. Fakhfouri, M. Striccoli, A. Voigt, G. Gruetzner, M. L. Curri, J. Brugger
P4.22 Characterization of nanocrystalline semiconductor/metal phthalocyanine hybrid junctions and
applications as photoconverter and sensor devices
C. Ingrosso, P. Cosma, P. Fini, M. L. Curri, G. Giancane, L. Valli, A. Agostiano
P4.23 Modification of UHMWPE processed by laser ion implantation
A. Lorusso, F. Paladini, L. Velardi, D. Margarone, N. Campo, L. Torrisi, V. Nassisi
P4.24 Structure, orientational order and dynamics of HAB by 2H and 13C NMR spectroscopy and DFT
calculations
Alberto Marini, Lucia Calucci, Marco Geppi, Carlo Alberto Veracini
P4.25 Surface structure of nanohydroxyapatite: effects on water and protein adsorption
Luca Bertinetti, Raffaella Ceschino, Gabriele Alberto, Daniele Bollati, Gianmario Martra
P4.26 Structural and spectroscopic characterisation of Mo1-xWxO3-δ oxides.
S. Morandi, G. Ghiotti, M. C. Paganini, E. Giamello, M. Bini, D. Capsoni, V. Massarotti
P4.27 Redox behaviour of Co species in microporous CoAPO-5: a spectroscopic study
M. Vishnuvarthan, G. Berlier, E. Gianotti, D. Davit, V. Murugesan, S. Coluccia
P4.28 Effect of the substrate type/composition and deposition techniques on the photocatalytic activity of
semiconducting nanocrystalline films for environmental applications
A. Panniello, R. Comparelli, D. Diso, A. Licciulli, G. Mascolo, A. S. Franza, M. Striccoli, A. Agostiano, M.L. Curri
P4.29 Silver ions mediated photochemical synthesis of water soluble gold nanoparticles with control over
size and morphology
T. Placido, R. Comparelli, P.D. Cozzoli, M. Striccoli, G. Capitani, F. Giannici, M.L. Curri
P4.30 Protein Adsorption on Chemically and Topographically Nanopatterned Polymer Surfaces
C. Satriano, G.M.L. Messina, G. Marletta
P4.31 A quantum-mechanical study on the adsorption of CO on TiO2: comparison between the Lewis
acidity of the rutile (110) and the anatase (101) surfaces.
Jessica Scaranto, Santi Giorgianni
P4.32 Photocatalytic H2 production from water splitting on one step flame synthesised TiO2 and Au/TiO2
Elena Selli, Gian Luca Chiarello, Ilenia Rossetti, Lucio Forni
P4.33 Si nanocrystals obtained in SiO2 matrix by low energy ion implantation
L. Velardi, A. Lorusso, M. Traversa, P. Prete, V. Nassisi, N. Lovergine
P4.34 New methodology
themogravimetry
for
Brønsted
quantification
G. A. V. Martins, G. Berlier, G. Gatti, S. Coluccia, L. Marchese
16
in
microporous
materials:
FTIR
and
ELENCO POSTER PER LA SEZIONE
CHIMICA FISICA TEORICA E COMPUTAZIONALE
P5.1
DPD Simulations to investigate polymer nanocomposites morphology
E.Bianchino, S.Piotto, C. Sciancalepore, M. L. Curri, A. Agostiano, M. Striccoli, F.Ciriaco, F.Mavelli
P5.2 Polarizzabilità ed iperpolarizzabilità statiche di semplici molecole: studio degli effetti vibrazionali.
S. Bruzzone, U.T. Lamanna, C. Guidotti, G.P. Arrighini
P5.3 Characterization of a New Candidate as Contrast Agent for Magentic Resonance Molecular
Imaging
U. Cosentino, D. Pitea, G. Moro, G.A.A Saracino, L. Cipolla, M. Gregori, F. Nicotra, A. Villa
P5.4 Theoretical and experimental studies of layered alkylamine-aluminophosphates.
M. D’Amore, C.Bisio, G. Talarico, M. Cossi, L. Marchese
P5.5 Sviluppo e applicazione di metodi basati su Orbitali Molecolari Estremamente Localizzati
Michela Ghitti, Alessandro Genoni, Stefano Pieraccini, Maurizio Sironi
P5.6 Potenziali chimici in eccesso in liquidi ionici tramite 1D-RISM
M. Malvaldi, S.Bruzzone, C. Chiappe
P5.7 Synthetic, electrochemical and theoretical investigation of encumbered triangular cluster units
Gabriele Manca, Alberto Albinati, Samantha Bruzzone, Fabrizia Fabrizi de Biani, Carla Guidotti, Piero Leoni, Lorella
Marchetti, Swagat K. Mohapatra, Eliseo Ruiz, Piero Zanello
P5.8 Combined X-ray absorption spectroscopy and Molecular Dynamics study of the Hg2+ aqua ion.
Giordano Mancini, Nico Sanna, Vincenzo Barone, Paola D’Angelo, Giovanni Chillemi
P5.9 Ab Initio calculation and experimental determination of 13C And 19F Chemical Shielding Tensors of
some fluorinated toluenes dissolved in a nematic LC mixture
Alberto Marini, Donata Catalano, Benedetta Mennucci, Carlo Alberto Veracini
P5.10 A non conventional molecular dynamics approach for determining interactions in MAPKs protein
complexes.
M. C. Menziani, F.Filomia, F. De Rienzo
P5.11 Interpretation of CW-ESR spectroscopy of tempo-palmitate in the 5CB liquid crystal
Antonino Polimeno, Mirco Zerbetto, Paola Cimino
P5.12 Multivariate analysis of glass structures obtainted by molecular dynamics simulations
M. Pota, A. Pedone, G. Malavasi, M. Cocchi, U. Segre, M. C. Menziani
P5.13 Molecular dynamics simulation of carboxy and deoxy murine Neuroglobin
Massimiliano Anselmi, Beatrice Vallone, Maurizio Brunori and Alfredo Di Nola
P5.14 Studio DFT della riduzione catalitica di acetofenone ad 1feniletanolo mediante
[Ru(HPN)(pcym)Cl]+.
V.Verdolino, R.Cammi, P.Pelagatti, M.Balordi, C.Pelizzi
17
CONTRIBUTI ORALI
18
SEZIONE
CHIMICA FISICA BIOLOGICA ED AMBIENTALE
19
(MD) simulations and acquiring nanoscopic images by
means of AFM techniques. Our simulations indicate that
borax stabilizes nanochannel-like structures when at least
seven triplexes of polysaccharide are considered (see
figure). The simultaneous presence of different Sclg
triplexes in a narrow space strongly influences the
properties of confined water molecules in a manner
similar, under many aspects, to that of water molecules
inside ‘canonical’ nanochannels (e.g. carbon nanotubes).
As a consequence, also the conformational properties of
flanking regions of Sclg triplexes are influenced.
I1
New methods to study protein chemistry with
ATR infrared spectroscopy
Prof. Peter Rich
University College London, Glynn Laboratory of
Bioenergetics
New techniques that can be used in conjunction with
modern attenuated total reflection (ATR) infrared
microprisms will be described. These methods allow
proteins to be manipulated cyclically between different
states whilst simultaneously monitoring both mid-IR and
UV/visible/near IR changes, providing increased
flexibility in comparison to transmission methods of the
types of changes that can be induced in proteins and
allowing quantitative measurements of vibrational
changes associated with conversion between stable
catalytic reaction intermediates, ligand binding and
oxidation/reduction. Both hydrophobic and soluble
proteins can be analysed and the ability to induce
transitions repetitively allows IR difference spectra to be
acquired at a signal/noise sufficient to resolve changes
due to specific cofactors or amino acids that can often be
interpreted at the atomic level by standard IR methods of
comparisons with model compounds, by isotope and
mutation effects and, increasingly, by ab initio
simulations. Combination of such analyses with atomic
3D structural models derived from X-ray and NMR
studies can lead to a deeper understanding of molecular
mechanisms of enzymatic reactions.
Figure 1: Top view of final structure (5 ns) in the MD
simulations of scleroglucan with borax (left) and without
borax (right).
Furthermore, Differential Scanning Calorimetry (DSC)
data show that the well known conformational transition
occurring at 280 K for Sclg does not take place in the
presence of borax. The MD simulations show that such
lack of transition is a direct consequence of the presence
of borax, while the confinement effects of water
molecules appear to play a less important role. The role
of Na+ counterions in the hydrogel structure is also
investigated.
1. Coviello, T.; Grassi, M.; Palleschi, A.; Bocchinfuso, G.;
Coluzzi, G.; Banishoeib, F.; Alhaique, F. Int. J. Pharm., 2005,
289, 97-107. 2. Palleschi, A.; Bocchinfuso, G.; Coviello, T.;
Alhaique, F. Carbohydr. Res., 2005, 340, 2154-2162. 3.
Palleschi, A.; Coviello, T.;Bocchinfuso, G.; Alhaique, F. Int. J.
Pharm., 2006 , 322, 13-21.
O 1.1
A polysaccharide forming nanochannels in the
hydrogel phase: study of static and dynamic
effects induced by a soft-confinement.
Bocchinfuso Gianfrancoa, Mazzuca Claudiaa, Marletta
Giovannib, Coviello Tommasinac, Alhaique Francoc,
Palleschi Antonioa
a
Department of Chemical Sciences and Technologies,
University of Rome “Tor Vergata”, Via della Ricerca
Scientifica,
00133
Rome,
Italy,
[email protected]
b
Laboratory for Molecular Surfaces and Nanotechnology,
Dipartimento di Scienze Chimiche and CSGI, University
of Catania, V.le A. Doria 6, 95125 Catania, Italy.
c
Department of Chemistry and Technology of
Biologically Active Compounds, Faculty of
Pharmacy, University of Rome “La Sapienza”, P.le
Aldo Moro 5, 00185 Rome, Italy
O 1.2
Yeast Cytochrome c molecules immobilized on
carbon nanotubes: A Conductive Atomic Force
Microscopy characterization at the single
molecule level
Chiara Baldacchini, Laura Andolfi, Salvatore Cannistraro
BIOPHYSICS & NANOSCIENCE CENTRE, CNISM,
Università della Tuscia, P.le dell’Università, 01100
VITERBO, Italy.E-mail: [email protected].
The integration between metalloproteins and singlewalled carbon nanotubes (SWNTs) is an active field of
research, with the goal of optimizing electronic signal
transduction in advanced and highly sensitive nanobiosensors. A crucial role is played by the immobilization
strategy of proteins on SWNTs, because it determines the
molecular orientation, which may influence the
conduction properties. It is known that metalloproteins
adsorbed on SWNTs via amide bonds preserve their
redox functionality [1], but any characterization of the
single molecule conduction is still missing. To this aim,
Conductive Atomic Force Microscopy (C-AFM) is the
appropriate tool, since it can couple imaging at the single
molecule level of redox proteins with the investigation of
their conduction properties [2].
The polysaccharide Scleroglucan (Sclg) has been
successfully used for various applications (secondary oil
recovery, ceramic glazes, food, paints, cosmetics, etc);
from a structural point of view it exhibits a triple helix
conformation (triplex) both in aqueous solution and in the
solid state. It is known that the Sclg hydrogels are
influenced by the presence of borax, in terms of
reological and drug release properties1. In previous
works, we have shown that the presence of borax
stabilizes the inter-triplex interactions and that the
variation of the induced properties can be fully explained
considering that the Sclg triplexes can form nanochannellike structures2,3. Now, the stability of these aggregates
has been investigated by means of Molecular Dynamics
20
efforts are devoted to
correlating
the
mechanical properties
with
nucleotide
sequence
and
orientation.
Biotinylated oligos
are
covalently
immobilized onto a
tip array; streptavidin
is covalently attached
to a tipless cantilever.
When the cantilever
makes contact with the tip, biotin-streptavidin
conjugation establishes contact at a known position on
the oligomer. Retraction of the scanner results in
controlled stretching of the nucleic acid and mechanical
unfolding of streptavidin. The latter occurs at loads less
than that required to pull the nucleic acid off the tip.
Rapid refolding
of
streptavidin
enables replicate
measurements on
the same oligo.
This
strategy
provides a rapid
Approach
and
reliable
method
for
Retract
Rupture
Force
analysis of the
mechanical
Scanner Position (nm)
properties
of
these biomolecules that is free of the artifacts and
assumptions implicit in data acquisition and interpretation
found with conventional methods. The DNA stretching
event is studied throughout the acquisition of forcedistance curves. Cantilever deflection is monitored as the
tip and the beam are brought into contact (biotinstreptavidin conjunction occurs) and subsequently
separated. Upon retraction the biomolecule is stretched
and the force is recorded by the deflection on the
cantilever. The use of a tip array-tipless beam set up
instead of the common tip-substrate enables us to explore
several tips during the same experiment and to look for
the single molecule tips (there may be tips that have no
molecules or multiple molecules as well, but we are only
interested in the single molecule pulling events).
Fig. 1
0.3
Current (nA)
0.05
40nm
0.00
F=14nN
F=16nN
F=17nN
F=18nN
-0.05
-0.10
-1.0
-0.5
0.0
Voltage(V)
0.5
F=21nN
F=22nN
F=27nN
F=30nN
1.0
Current (nA)
0.10
Cantilever Deflection
We functionalized SWNTs with Yeast Cytochrome c
(YCC) molecules via amide bonds, as shown on the left
of Fig. 1. A representative 3D Tapping-Mode AFM
image of a functionalized SWNT on a gold surface is
shown on the right of Fig. 1. By means of C-AFM,
simultaneous topography and current images are obtained
(the current image of a functionalized SWNT is shown in
Fig. 2, left panel). By positioning the C-AFM tip on top
of a functionalized SWNT, we can record, as a function
of the applied bias (I/V), the current flowing between tip
and metal substrate, i.e. through both the SWNT and the
adsorbed protein. Series of I/V curves have been recorded
as a function of the applied force load (a representative
set is shown in the central panel of Fig. 2). The current
present a typical increasing-decreasing behaviour as a
function of the applied force, indicative of the presence of
SWNTs (the current recorded through YCC molecules
adsorbed on bare gold surfaces always increases with the
applied force, until the protein break [3]). Moreover, by
using SWNTs as spacers between redox proteins and
metal surfaces, at low applied bias, lower applied forces
are needed to record higher currents, with respect to
proteins directly assembled on gold surfaces (see Fig. 2,
right panel).
YCC/Au
F = 42 nN
YCC/SWNT/Au F = 18 nN
0.2
0.1
Fig. 2
0.0
0.0
0.1
0.2
0.3
0.4
0.5
Voltage (V)
As a future perspective, we will investigate the role
played by the protein-SWNT interaction in the transport
mechanism, by comparing the conductive behaviour of
YCC molecules as a function of the immobilization
strategy on the SWNT sidewalls.
1. Gooding, J. J.; Wibowo, R.; Liu, J.; Yang, W.; Losic, D.;
Orbons, S.; Mearns, F. J.; Shapter, J. C.; Hibbert, D. B.; Journal
of the American Chemical Society, 2003, 125, 9006 - 9007. 2.
Andolfi, L.; Cannistraro, S.; Surface Science, 2005, 598, 68 – 77.
3. Delfino, I.; Bonanni, B.; Andolfi, L.; Baldacchini, C.;
Bizzarri, A. R.; Cannistraro, S.; Journal of Physics:Condensed
Matter, 2007, 19, 225009 – 225027.
Lebrun and Lavery1 have predicted that the stretching of
DNA will differ markedly with its orientation. To test this
prediction, we have constructed three oligos of exactly
the same sequence, biotinylated at either the 5' or 3'
terminus and possessing an amino anchoring moiety at
the other terminus, (i.e. 5'-5', 3'-3' modified oligos). Each
was subjected to AFM-based stretching. The resultant
force curves were statistically analyzed and compared
with theory . In this presentation, we critically examine
our experimental approach and findings in light of the
prediction.
O 1.3
AFM force curve investigation of DNA elasticity
Benedetta Carlottia, Fausto Eliseia, Loredana Latterinia,
Lawrence A. Bottomleyb, Nicholas V. Hudb, Catherine T.
Santaib.
a
Dipartimento di Chimica and Centro di Eccellenza per i
Materiali Innovativi Nanostrutturati-Universita’ degli
Studi di Perugia, Via Elce di Sotto n.8, 06123 Perugia,
[email protected]
b
School of Chemistry and Biochemistry-Georgia Institute
of Technology, 311 Ferst Drive, N.W., 30332-0100
Atlanta, GA, USA
1. Lebrun, A.; Lavery, R.; Nucleic Acids Research, 1996,
24(12), 2260 – 2267.
Atomic force microscopy is a useful tool for determining
the mechanical properties of single biomolecules. Our
21
we will tackle the problem of minimal ‘lipid-peptide’
cells (see Figure 1), already introduced in our recent
worksv. In particular, we will investigate the possibility
that molecular transport across the cell membrane
mediated
by
polypeptides
channels
can
be
activated/deactivated by the elastic energy of the lipid
bilayer and, as a result, function as a primitive
mechanism for protocells to regulate their growth and
reproduction.
2) Second, we aim to develop a model that addresses
more directly the problem of bridging the gap between
experimental (in vitro) and theoretical (in silico) resultsii.
Specifically, we would model the experimental structural
and kinetic properties of vesicular aggregatesvi and
address the differences between standard lipid and fatty
acid vesiclesvii, including the possible transition from one
to the other, since the former are closer to present
biomembranes but the latter have higher prebiotic
relevance.
O 1.4
Stochastic simulations of proto-cell dynamics.
F.Mavellia, K.Ruiz-Mirazob, F.Ciriacoa, U.T.Lamannaa
a
Chemistry Department, University of Bari, Via
Orabona 4 – 70125 Bari
b
Biophysics Research Unit (CSIC-UPV/EHU) University
of the Basque Country, Spain
A computational platform developed to simulate the
stochastic time evolution of homogeneous, fixed-volume,
chemically reacting systemsi has been recently extended
to apply it to volume-changing, globally heterogeneous,
systemsii. This improvement made the software
‘ENVIRONMENT’ suitable for developing and testing
realistic proto-cell models and possible explanations for
their spontaneous emergence in pre-biotic conditions. In
fact, we defend a viewiii that puts proto-metabolic cellular
organization at the core of the problem of the transition to
life, in contrast with the mainstream research in the field,
which considers the synthesis and properties of
biomolecules (‘self-replicating’ RNA or DNA) as the key
point. A much more plausible prebiotic scenario involves
the early appearance of compartmentsiv and their ‘coevolution’ with reaction networks, so that both get
increasingly complex, until the living threshold is
eventually achieved. In this framework, lipid membranes
can not be considered as mere containers of a set of
reactants in relevant concentration levels, but as a
supramolecular structure that plays a crucial role in the
control of the matter-energy flow through the system, by
means of very diverse transport and transduction
mechanisms. In order to test and further elaborate our
ideas and working hypotheses, as well as their
theoretical/experimental implications, we will use the
computational approach and the ENVIRONMENT
program to simulate the stochastic time behaviour of
realistic proto-cellular models, i.e. models that can be
tested in vitro or that can suggest real lines of
experimental research, trying to bridge the traditional gap
between theorists and experimentalists.
There are two main lines of research we would like
to illustrate in this contribution:
1) First, we will explore how far it is possible to go with
cell models that keep a low degree of molecular
complexity, i.e. made of relatively simple and, therefore,
prebiotically plausible components, like fatty acids,
aminoacids and short peptide chains. More concretely,
i
Mavelli F.,Piotto S.J. Mol.Struct. 2006, 771 55
Mavelli F.,Ruiz-Mirazo K., Phil.Trans.R.Soc.B. 2007 (in
press); Orig.Life Evol.Biosphere, 2007 (in press).
iii
Ruiz-Mirazo K.,Moreno A., Artificial Life 2004, 10(3), 235
iv
Luisi, P. L., The Emergence of Life, 2006 Cambridge
University Press, Cambridge
v
Ruiz-Mirazo K., Mavelli F. Orig. Life Evol. Biosphere 2007
(in press); BioSystems, 2007, (accepted).
vi
Chen, I., Roberts R.W., Szostak J.W., Science 2004, 305,
1474; Chen, I., Szostak J.W., Biophysical Journal, 2004,87, 988.
vii
Cheng, Z., Luisi P.L, J.Phys.Chem.B, 2003, 107, 10940; S.
Rasi, F. Mavelli, P.L. Luisi,, J. Phys. Chem. B, 2003, 107,
14068; Rasi, S., Mavelli F., Luisi P.L., Orig.Life Evol.Biosphere,
2004, 34, 215
ii
O 1.5
ATPasi di tipo P in modelli di membrane
biologiche: studio delle proprietà funzionali
M.R. Moncelli, G. Bartolommei, F. Tadini-Buoninsegni
Dipartimento di Chimica, Università di Firenze,
BioElectroLab, via della Lastruccia 3, 50019 Sesto
Fiorentino (FI); [email protected]
Nel nostro laboratorio si studiano da diversi anni proteine
di membrana in modelli sperimentali di membrane
biologiche. In modo particolare si studiano ATPasi di
tipo P con metodi chimico fisici. Recentemente abbiamo
focalizzato la nostra attenzione sullo studio delle
interazioni della Ca-ATPasi e della Na,K-ATPasi con
alcuni farmaci. Si illustreranno:
- le caratteristiche generali delle ATPasi;
- i metodi di indagine utilizzati: a) spettrofluorimetria con
sonde stiriliche elettrocromiche e b) tecnica per salti di
concentrazione su SSM (Solid Supported Membrane)1,2.
Si presenteranno alcuni risultati:
- interazione della Ca-ATPasi con inibitori a differente
affinità
(clotrimazolo
[3],
tapsigargina,
acido
ciclopiazonico, curcumina);
- interazione della Na,K-ATPasi con clotrimazolo.
1. Tadini-Buoninsegni, F.; Bartolommei, G.; Moncelli, M.R.;
Inesi, G.; Guidelli, R.; Biophys. J., 2004, 86, 3671-3686. 2.
Tadini-Buoninsegni, F.; Bartolommei, G.; Moncelli, M.R.;
Guidelli, R.; Inesi, G.; J. Biol. Chem., 2006, 281, 37720-37727.
3. Bartolommei, G.; Tadini-Buoninsegni, F.; Hua, S.; Moncelli,
M.R.; Inesi, G.; Guidelli, R.; J. Biol. Chem., 2006, 281, 95479551.
Fig. 1: Schematic draw of the minimal lipid-peptide
cell.
22
Compaction of nucleosomes in chromatin in vivo depends
on their positioning along DNA and therefore on the
DNA linkers that bridge and mutually rotate the adjacent
nucleosomes in the space. Experimental data reveal the
presence of some regularity in which the nucleosome
repeat length in chromatin fibers differs of multiple of
about 10 bp. This suggests the existence of orientational
constraints between the nucleosomes and between
nucleosomes and the fiber axis as well. Moreover,
experimental evidence indicates that the nucleosome
super-helical axis is nearly perpendicular to the fiber axis.
Recently, the elucidation of the X-ray crystal structure of
a reconstituted nucleosome tetramer array (2) and the
more recent proposal of the 30 nm fiber interdigitated
structure based on the interpretation of EM and cryo-EM
images of multimeric nucleosome arrays (3), suggest two
apparently different architectures of chromatin fibers.
The two models of chromatin are reported in the figure:
A) the single helix model with inter-digitized
nucleosomes as proposed by Rhodes and cows (3), B) the
two-start helix with straight linkers as suggested by
Richmond and cows (2).
The crystal structure of the tetranucleosome shows that
linker DNA zigzags back and forth between two stacks of
nucleosome cores, which appears to form a truncated
two-start helix. This nucleosome organization however
appears to be not consistent with the EM experiments that
are characterized by a more compact packing of
nucleosomes and interpreted with an inter-digitized
model (3). Furthermore, the modular increasing of linker
lengths by 10 bp results in an apparent transition of
nucleosome density along the fiber and radial dimension
occurring at multimeric DNA periodicity between 207
and 217 bp.
Therefore, the sequential organization of nucleosomes
remains a still controversial question.
A theoretical study of the possible nucleosome packing in
the chromatin fiber is proposed. Some general features of
the fiber structure emerge. The nucleosome density along
the fiber and the orientation of nucleosome helical axis
with respect to the local fiber axis strongly discriminate
the possible architecture of nucleosome assembly and the
path of DNA linkers, under the hypothesis of the
minimum distortion of the nucleosome and linker DNA
intrinsic structure.
In fact, the packing resulting from the EM visualizations
of a nucleosome array in the chromatin 30 nm fibers is
mainly dependent on the orientational parameters. Their
study however implicitly produces useful suggestions
about the structure and mutual arrangement of the linkers.
Assuming the X-ray crystal structure for the nucleosome
and the dinucleosome as a repeating unit of the chain, the
helical parameters of the fiber and the orientation of the
nucleosome axis with respect to the fiber axis are
obtained in terms of the internal twist of the two linkers
connecting adjacent nucleosomes. The results indicate
that fixing the orientational parameters strongly restricts
the linker length to values that differ by integral turns of
double helix. However, the linker lengthening by DNA
steps of 10 bp increases twist deviation from integral
turns of the canonical B-DNA, which is characterized by
a periodicity of 10.4 bp. As a consequence, the
conservation of a basic structure stable at lowest linker
length results in the increasing of the torsional energy,
which can be the driving force of a transition to a
different class of structures. This is also due to the
progressive relaxing of inter-nucleosome contacts
consequent to the increase of the radial dimension of the
fiber.
Considering the nucleosome packing as a function of
O 1.6
Physico-chemical aspects of peptide adsorption
onto hydrophilic and hydrophobic substrates
Cristina Satriano, G.M.L. Messina and Giovanni Marletta
Laboratory
for
Molecular
Surfaces
and
Nanotechnologies (LAMSUN) - Dept. of Chemical
Sciences - University of Catania and CSGI, viale A.
Doria 6- 95125 Catania, Italy. [email protected]
The cell-adhesive peptide sequences PHSRN and RGD
were adsorbed onto hydrophobic polysiloxane surfaces
(HYB) and the corresponding hydrophilic ones (HYL)
obtained by UV-O3 treatments of the HYB surfaces.
Peptides adsorption kinetics as well as coverage and
orientation were investigated by Quartz Crystal
Microbalance with Dissipation monitoring (QCM-D) and
Atomic Force Microscopy (AFM) measurements.
Two different adsorption mechanisms were observed,
consisting in a “Langmuir-like” process, with
adsorption/desorption equilibrium of basically random
coiled molecules, and a “Lundstrom-like” process,
involving the irreversible adsorption probably due to the
change in the peptide conformation.
The first process was shown to occur for PHSRN onto
HYB substrates and RGD on both HYB and HYL
substrates, while the second one occurred only for
PHSRN onto HYL surfaces. The biological response of
bare and peptide-immobilized surfaces was tested by
studying their short term interaction with McCoy
fibroblast cells by means of QCM-D and optical
microscopy for 2 hours incubation in medium-free
solutions.
It turned out that both peptide immobilized-HYL as well
as control HYL surfaces exhibited a larger number of
adhered and viable cells compared to the HYB ones.
Moreover, it was found that only PHSRN-HYL substrates
prompt the cell spreading process.
The observed effects have been interpreted in terms of
the different adsorption state of immobilized peptides on
the various surfaces, depending on the tuning of peptide
and surface charges, or the occurrence of preferential
PHSRN unfolding processes on the highly polar HYL
surfaces.
O 1.7
Structural analysis of 30 nm chromatin fiber
architecture.
A. Scipionia, S. Morosettib, G. Turchettib, P. De Santisb
a
Dipartimento di Chimica, La Sapienza Università di
Roma, Piazzale A. Moro, 5, 00185 Roma;
[email protected]
b
Dipartimento di Chimica, La Sapienza Università di
Roma, P. le A. Moro5, 00185 Roma, Italy
Chromatin architecture plays an important role in the
regulation of nuclear processes of the eukaryotic
genomes. It is the result of complex hierarchic assembly
of a nucleosome array in a compact structure.
Although the nucleosome structure is known in its
molecular details at near-atomic resolution (1), the most
fundamental information about the pattern of the
organization of nucleosomes in the chromatin fiber is still
debated and not fully clarified.
23
a
couples of linkers, which determine the mutual
arrangement of three adjacent nucleosomes, permits to
analyze all the possible assemblies where the interactions
between alternating nucleosomes are determinant in the
fiber best packing. In particular, we analyzed the
architectures characterized by high nucleosome density as
those indicated by EM visualizations ranging between 10
and 15 nucleosome per 11 nm for DNA multimeric
repeats from 177 to 237 bp, with a fixed increment of 10
bp.
The conformational map of the angles between the
nucleosome helical axis and the chromatin fiber axis
shows that the possible structures should lie in those
regions where one or both the twist angles correspond to
the adjacent nucleosomes in trans with respect to the
linker.
In the same angular positions high nucleosome packing
density, given as the number of nucleosomes in a helical
slice of 11 nm, lies nearby the inversion of fiber chirality
through formal planar spires where the helical repeat
vanishes.
In a previous paper we tried to analyze the nucleosome
packing adopting a rough model, where the nucleosomes
were modeled as oblate symmetrical tops with
dimensions resembling those of the crystal structure. The
best packing was driven using an appropriate Gay-Berne
potential for oblate ellipsoids (4). At present, we are
refining our model by evaluating the energy map taking
into account the interactions between all the DNA
phosphate groups adopting a Lennard-Jones potential
with the minimum localized at 7 Å so that the
nearest-neighbor DNA axes lie at a distance of about 26
Å, as found in DNA fibers. The histone octamer is not
considered; as a consequence the energy map represents a
necessary but not sufficient condition for localizing the
nucleosome best packing. Nevertheless, the obtained
results permits to identify a class of architectures that
account for the experimental data and suggest interesting
and dynamical features of chromatin fibers.
CNISM e Dipartimento di Scienza dei Materiali,
Università di Milano Bicocca, via R. Cozzi 53, 20125
Milano, [email protected]
Chemical sensing has a self-evident relevance to modern
robotics. Improvements in the capabilities of detecting
chemicals in solution and gas phase has an immediate
impact on a variety of fields, such as environmental
monitoring, food quality assurance, chemical plant
control, and biomedical analyses. However, further to its
applications, chemical sensing is also a promising arena
where nanotechnology and bioinspired strategies can
meet. In this contribution recent advances in the
development of a novel class of bioinspired gas sensors
will be presented.
An approach based on the use of covalent organic
moieties grafted onto single-crystal Si surfaces has been
developed in recent years at the University of Milano
Bicocca. An organic moiety gets covalently grafted by
wet chemistry methods onto a Si surface, and a MetalInsulator-Semiconductor (MIS) junction is obtained
thereof, where the grafted monolayer plays the role of the
insulator, and a metal layer is intentionally deposited on
top of it as a discontinuous ultrathin film so as to allow
gas to diffuse toward the grafted Si surface. Upon
molecular recognition of the target gas molecule, the
additional dipolar momentum associated to the gas
molecule oriented by the interaction with the grafted
layers is expected to lead to a modulation of the barrier
height at the MIS junction.
To quantitatively verify the detection mechanism, a Hterminated Si(100) surface was hydrosilylated [1-4] with
substituted phenylacetylenes using [HRu(CO)(PPh3)3Cl]
as catalyst. Two types of grafted surfaces were studied,
functionalized with either the benzyl ester of 1-vinyl-4carboxy-benzene or its relevant acid. A lift-off technique
was adopted [5] to prevent the damage of the organic
monolayer upon metal deposition. Current-voltage
characteristics were measured by exposing the MIS
device to NH3 in synthetic air at different temperatures to
verify their sensing capabilities and to investigate the
pertinent detection mechanism.
An extension of Campbell’s model [6] for a grafted Sibased MIS junctions was proposed [7] and systematically
compared with the experimental dynamic barrier height
modulation in the presence of ammonia. The model was
found to be in excellent agreement with the experimental
data in the whole range of gas partial pressure considered.
The results have a general relevance for sensing devices
where the modulation of the barrier heights by molecular
units assembled or grafted onto semiconductors. Further
patented applications to gas sensing [8] will be briefly
outlined.
1. Luger, K.; Mäder A. W.; Richmond R. K.; Sargent D. F.;
Richmond T. J.; Nature, 1997, 389, 251-260.
2. Schalch T.; Duda S.; Sargent D. F.; Richmond T. J.; Nature,
2005, 436, 138-141.
3. Robinson, P. J. J.; Fairall, L.; Huyhn, V. A. T.; Rhodes, D.;
Proc. Natl. Acad. Sci. USA, 2006, 103, 6506-6511.
4. Besker N; Anselmi C; Paparcone R.; Scipioni A.; Savino M.;
De Santis P.; FEBS Lett., 2003, 554, 369-372.
1. Sudo, T.; Asao, N.; Yamamoto, Y.; Journal of Organic
Chemistry, 2000, 65, 8919 – 8923. 2. Katayama, H.; Taniguchi,
K.; Kobayashi, M.; Sagawa, T.; Minami, T.; Ozawa, F.; Journal
of Organometallic Chemistry, 2002, 645 (1-2) 192 – 200. 3.
Wojtyk, J.T.C.; Morin, K.A.; Boukherroub, R.; Wayner,
D.D.M.; Langmuir, 2002, 18, 6081 – 6087. 4. Wu, W.; Li, C.J.;
Chemical Communications, 2003, 14, 1668 – 1669. 5. Vilan, A.;
Cahen, D.; Advanced Functional Materials, 2002, 12, 795 –
807. 6. Campbell, I.H.; Rubin, S.; Zawodzinski, T.A.; Kress,
J.D.; Martin, R.L.; Smith, D.L.; Barashkov, N.N.; Ferraris, J.P.;
Physical Review B, 1996, 54, 14321 – 14324. 7. Oldani, M.;
Narducci, D.; Taffurelli, A.; Surface Science, 2007, in press. 8.
Narducci, D.; European Patent, 2006, PCT/EP2006/001570.
O 1.8
Bioinspired Chemical Sensing: Molecular
Recognition
of
Gaseous
Species
at
Nanostructured Surfaces
Dario Narduccia, Edoardo Di Vitaa, and Jenni Portmana
24
SEZIONE
SPETTROSCOPIA E FOTOCHIMICA
25
O 2.1
I2
Struttura e reattività di molecole isolate e
clusters
Calculation of EPR parameters in solution by a
recent integrated computational approach
Maurizio Becucci
Dipartimento di Chimica, Università di Firenze, v.
Lastruccia 3, 50019, Sesto Fiorentino (FI),
[email protected]
LENS, v. Carrara 1, 50019 Sesto Fiorentino (FI)
Paola Cimino&‡, Orlando Crescenzi&and Michele Pavone&
&
Università di Napoli, “Federico II”, Complesso
Universitario di Monte Sant’Angelo Via Cintia, I-80126
Napoli, Italy.
‡
Permanent Address: Dipartimento di Scienze
Farmaceutiche Università di Salerno Via Ponte Don
Melillo 84084 Fisciano-Salerno, Italy
Lo studio con metodi di spettroscopia laser di specie
molecolari (sia molecole isolate che piccoli aggregati
molecolari) raffreddati in jet supersonici permette di
ottenere moltissime informazioni che riguardano sia la
geometria d’equilibrio di questi sistemi che la dinamica
di eventuali processi fotochimici.
La prima parte della comunicazione riguarderà la
determinazione della struttura di diversi complessi che
contengono molecole aromatiche. In particolare ci siamo
interessati sia dei dimeri formati da queste molecole che i
complessi bimolecolari formati per interazione con
acqua, ammoniaca e metanolo. La topologia e la natura
dell’interazione cambiano in maniera sostanziale nei
diversi sistemi studiati. L’indagine è stata condotta sia
per mezzo di spettroscopia elettronica (di ionizzazione
multifotonica e LIF ad alta risoluzione in frequenza) che
per mezzo di calcoli a diverso livello di teoria.
La seconda parte introdurrà i nuovi risultati che abbiamo
ottenuto nel campo della dinamica di reazione chimica
con l’uso di tecniche di ion imaging.1 Si tratta di un
metodo d’indagine particolarmente efficace nello studio
dei processi unimolecolari di fotodissociazione.
L’assorbimento di un primo fotone da parte della
molecola d’interesse innesca la reazione di dissociazione.
I frammenti così prodotti sono ionizzati selettivamente da
un secodo fotone. Questi ioni sono poi proiettati su un
rivelatore bidimensionale da un sistema di ottiche
elettrostatiche. Il punto d’arrivo sul rivelatore è legato
alla velocità acquisita dal frammento nella dissociazione.
La misura del modulo della velocità dei frammenti e della
loro distribuzione angolare ci permette di entrare nel
dettaglio del processo reattivo. Come esempio
mostreremo uno studio sulla fotodissociazione del Nmetilpirrolo per eccitazione a 193 nm in cui si osservano
due diversi meccanismi di reazione corrispondenti al
distacco di frammenti metile con alta e bassa energia
cinetica. La reattività osservata sarà discussa anche alla
luce dei risultati pubblicati molto di recente sulla
fotodissociazione del pirrolo.2
Interpretation of structural properties and dynamic
behaviour of molecules in solution is of paramount
relevance for a better understanding of their stability,
chemical reactivity, catalytic action. Information can be
gained, in principle, by a variety of spectroscopic
techniques, magnetic as well as optical. In particular,
continuous wave electron spin resonance (cw-ESR)
measurements are highly informative. However, the
wealth of structural and dynamic information which can
be extracted from ESR spectroscopy is, at present,
limited by the necessity of employing computationally
efficient models, which are increasingly complex for the
need of taking into account diverse relaxation processes
affecting the spectrum.
Here, we present selected examples where the role of
stereo-electronic, environmental and short-time dynamic
effects in tuning the hyperfine and gyromagnetic tensors
of prototypical nitroxide spin probes has been
investigated by an integrated computational approach
based on molecular dynamics and discrete-continuum
solvent models. The methods are based on a high-level
DFT approach coupling the PBE0 hybrid functional with
a tailored basis set, and with proper account of specific
and bulk solvent effects.
The computed magnetic parameters are in satisfactory
agreement with the available measured values, and allow
for an unbiased evaluation of the role of different effects
in tuning the overall EPR observables.
1. M.Pavone; P.Cimino; F. De Angelis; V.Barone;, J. Am.
Chem.Soc., 2006, 128, 4338-4347.
2. M. Pavone; A. Sillampae; P. Cimino; O. Crescenzi; V.
Barone, J. Phys. Chem. B, 2006, 110, 16189-16192.
3. P.Cimino; M.Pavone; V.Barone, Chem. Phys. Lett., 2006,
409, 106-110.;
Nel corso di questo lavoro M.B. ha beneficiato di una
Marie Curie fellowship (MTKD-CT-2004-BICAL509761).
O 2.2
1. Bowen, M. S.; Becucci, M.; Continetti, R. E., J. Chem. Phys.,
2006, 125, 133309. 2. Ashofold, M. N. R.; Cronin, B.; Devine,
A. L.; Dixon, R. N.; Nix, M. G. D.; Science, 2006, 312, 1637.
Flexible nano-photo-electrochromic film
Giovanni De Filpoa, Fiore P. Nicolettab, and Giuseppe
Chidichimo
a
Dipartimento di Chimica, Università degli Studi della Calabria,
87036 Rende (CS), Italy, [email protected]
b
Dipartimento di Scienze Farmaceutiche, Università
degli Studi della Calabria, 87036 Rende (CS), Italy
A flexible nano-photo-electrochromic PET-TiO2-PO4Methylene Blue based film was obtained by the
deposition of TiO2 nanoparticles on a PET conductive
substrate. A further covalent chemical bond of
Methylene Blue (MB) molecules on the TiO2 film by
means of phosphate groups, ensures the photoelectrochromic properties of this device. Indeed, MB
26
molecules can change color both owing to the irradiation
with red light, in the presence of electron donor
molecules, and to the oxidation reaction with an
oxidizing agent. Since the oxidation reaction of MB
molecules occurs at the same electrode where the
molecules are anchored, the film shows a very fast
coloration time (600 ms).
The thermal stability of the film and the anchoring of
MB molecules on TiO2 nanoparticles was investigated
by Differential Scanning Calorimetry (DSC) technique.
Morphology of the surface and cross section of TiO2
layer was studied by Scanning Electron Microscope
(SEM). Moreover the device was characterized in terms
of light absorption by UV-Visible spectroscopy and
optical transmission by an optical line.
nonlinear response. The TPA spectrum shows also a
band at 410 nm, clearly visible in the aggregate spectrum,
but apparently lacking in the one of the monomer. The
TA spectra should display also a transient band in the
NIR region, due to absorption from the Q-state of the
TPPS towards the 410 nm state. Because of this, we have
mainly investigated the TA of the monomer and Jaggregate in this spectral region and observed a clear TA
band for the J-aggregate, while only residual TA and no
clear band is present for the monomer. This is the first
time, to our knowledge, that a state, falling at energies
lower than the lowest two exciton band is observed in the
TA spectrum of a molecular aggregate in solution. The
nature of this state is discussed on the basis of the
excitonic theory for molecular aggregates.
1. J-Aggregates; Kobayashi, T., Ed.; World Scientific:
Singapore, 1996.
2. Collini, E; Ferrante, C; Bozio, R; J. Phys. Chem. B, 2005,
109 (1), 2 -5.
O 2.4
Importance of the hydrogen bond in tautomeric
equilibria and in molecular complex formation.
Rotational
spectroscopy
in
supersonic
expansions
Sonia Melandria, Barbara Michela Giulianoa, Assimo
Marisa, Biagio Velinob, Laura Favero,c Walther Caminatia
a
Dipartimento di Chimica “G. Ciamician”, via Selmi 2,
I-40126 Bologna, [email protected]
b
Dipartimento di Chimica Fisica e Inorganica
dell’Università, Viale Risorgimento 4,
I-40136
Bologna, Italy
c
Istituto per lo Studio dei Materiali Nanostrutturati
(ISMN, Sezione di Bologna), CNR, via Gobetti 101, I40129 Bologna, Italy.
O 2.3
Role of excitonic interactions on the nonlinear
absorption spectra of porphyrin J-aggregates
Elisabetta Collini, Camilla Ferrante, Renato Bozio
Dipartimento di Scienze Chimiche e UdR INSTM di
Padova, Università di Padova, Via Marzolo 1, I-35131
Padova, Italy
The importance of weak interactions, especially inter and
intramolecular hydrogen bonds, is recognized in all areas
of chemistry and biology and the understanding of their
role is essential to explain and model many phenomena.
In our studies the detailed nature of such interactions is
revealed by high resolution spectral data on isolated
molecules and molecular complexes observed in free jet
expansions. The interpretation of these data is assisted by
high level quantum chemical calculations and other
models to help justify and rationalize the results.
We report microwave spectroscopy studies on molecules
isolated in supersonic expansions: 4-hydroxypyrimidine,1
methylsalycilate and erythritol, and show the importance
of hydrogen bond formation on the shape of the
tautomeric and conformational potential energy surface
and on the geometry of the stable structures.
The study of small molecular hydrogen bonded
complexes such as dimers or trimers is also very
interesting and can be considered a starting point towards
the understanding of bulk properties.
Weak and strong intermolecular hydrogen bonds (CH...F, C-H...N, O-H...N) can be observed in the structures
of the trimer of difluoromethane,2 pyridine- CHF3 or
pyridine-water. These molecular complexes are stabilized
by more than one hydrogen bond but they are also highly
dynamical.
Tetrasolphonatophenyl-porphyrin (TPPS) is a water
soluble porphyrin capable to form J-type aggregates at
pH < 4, when the diacid form is present. Dimension and
shape of these aggregates depends on several factors such
as: concentration, ionic strength of the solution, and
solvent nature. The electronic properties of the TPPS
molecule are strongly influenced by the aggregation
process, as clearly shown by the linear absorption
spectrum.1
We will present the two photon absorption (TPA) and the
transient absorption (TA) spectra of diacid TPPS in water
solution, both as a monomer and in the J-aggregate form.
The spectra are measured with ultrashort laser pulses,
employing the pump and probe technique. In particular
TPA and TA differ for the wavelength employed for the
pump pulse, being not resonant for TPA, and resonant for
the TA. Therefore TPA is a coherent technique,
investigating two photon allowed excited states, while
TA investigates the incoherent population of the first
excited state, followed by transient absorption towards
higher two photon allowed states. The TPA cross section
of TPPS in the J-aggregate form is thirty times more
intense than in the monomer in the whole spectral range
investigated (380-430 nm).2 Such an enhancement can be
exploited to build molecular devices with a high and fast
27
1. Sanchez, R.; Giuliano, B.M.; Favero ,L.B.; Caminati, W., J.
Am. Chem. Soc., 2007, 129, 6287-6290
2..Blanco, S.; Melandri, S.; Ottaviani, P.; Caminati,
W.; J. Am. Chem. Soc.; 2007; 129(9), 2700 –
2703
O 2.6
Photocatalytic activity of surface fluorinated
and/or Au-modified titanium dioxide
Elena Selli
Dipartimento di Chimica Fisica ed Elettrochimica,
Università degli Studi di Milano, Via Golgi 19, 20133
Milano, [email protected]
O 2.5
Titanium dioxide particles were modified either by gold
nanoparticles deposition (Au/TiO2) or by surface
fluorination (F-TiO2) and their photocatalytic activity was
tested in the degradation of organic substrates in aqueous
suspension, in order to assess the effects of noble metal
deposition and of a hydrophobized oxide surface on the
electron transfer processes occurring at the
semiconductor – water interface under irradiation with
light of different wavelength. The primary photocatalytic
processes involving photopromoted conduction band
electrons, eCB–, and valence band holes, hVB+, were
investigated during the photodegradation runs, either by
monitoring the evolution of hydrogen peroxide, formed
through adsorbed dioxygen reduction by eCB–, or by EPR
measurements of the DMPO-OH adduct produced by
spin trapping of hydroxyl radicals formed through water
or hydroxyl anions oxidation by hVB+, or eventually by
other photoproduced oxygen species.
Surface fluorination of TiO2 strongly modifies its surface
properties. Indeed, the fast adsorption of fluoride anions
on the semiconductor surface decreases the amount of
surface hydroxyl groups, leading to the formation of ≡TiF species, which dominate at acidic pH [1], with an
almost complete displacement of surface –OH groups at
pH 3.7. Nanosized noble metal isles were deposited on
TiO2 particles mainly through the well established
deposition-precipitation method [2], employing different
pH adjusting media, or by immobilization of preformed
metallic sols [3]. In this case a pre-irradiation step was
necessary, to remove the organic species surrounding
gold nanoparticles. This produced only a slight increase
of the size of Au isles (from ca. 2 to ca. 5 nm, on
average), as revealed by HRTEM analysis.
The photocatalytic degradation of aromatic moieties –
containing substrates was markedly faster on F-TiO2 than
on unmodified TiO2, in line with an enhanced hydroxyl
radical formation. Indeed, EPR spin trapping
measurements revealed that titanium dioxide surface
fluorination leads to an increased concentration of the
DMPO-OH adduct in the aqueous phase under irradiation
[4]. By contrast, the photocatalytic degradation of formic
acid was slower upon TiO2 fluorination, but, at the same
time, hydrogen peroxide concentration was much higher
than on unmodified TiO2. The peculiar role played by the
CO2•- species, produced from formic acid oxidation, in
H2O2 formation during the photocatalytic degradation of
this latter on F-TiO2. could thus be fully enlightened [5].
The main effect of surface fluorination thus appears to
consist in its shielding effect at the semiconductor-water
interface, which favours the desorption of photogenerated
active species.
Gold nanoparticles deposition on TiO2 produced much
lower, though wavelength dependent, increases in the
photocatalytic degradation rates of organic substrates.
Maximum degradation rates were attained for different
metal loadings, depending on the deposition procedure,
allowing an optimum balance between the detrimental
shielding effects of Au surface nanoparticles, which
decrease the fraction of light absorbed by TiO2, and their
beneficial role in capturing photopromoted eCB–, thus
decreasing the eCB– - hVB+ recombination rate [3].
Trehalose and glucose dynamics by lowfrequency scattering techniques
A. Morresi,a M. Paolantoni,a P. Sassi,a M. E. Gallina,a D.
Fioretto,b L. Comez,b F. Scarponib
a
Dipartimento di Chimica, Università di Perugia, Via
Elce di Sotto, 8, I-06123 Perugia, Italy
b
Dipartimento di Fisica, Università di Perugia, Via
Pascoli, I-06123 Perugia, Italy
Studies of carbohydrates in aqueous solutions have been
performed by different experimental techniques –
molecular dynamics simulation, neutron scattering, time
and frequency domain spectroscopies – in order to
ascertain their important specific structural and
dynamical properties, especially cryo-conservative ones.
Nevertheless a definite molecular picture of the examined
systems is not yet available.1 Moreover, the different
abilities of some important mono- and di-saccharides in
long-term storage of biological materials have not been
clarified so far.
Often it is suggested that the different hydrogen bond
networks formed by the different sugars in water should
be the principal responsible of their distinct bioprotective behaviour.
Concerning the water properties, they are among the most
discussed and debated ones; in particular, different
experimental measurements describe a complex picture
with dynamical regimes following one upon the other:
each experimental probe sheds light on a limited window
of the whole dynamics, describing a single process, in a
specific time range, within the femto- to milli-second
region.
The water properties inside the solutions depend on the
relative distance between solute and solvent molecules:
the molecules in the immediate vicinity of the solute are
called “biological water”, in opposition to the rest, the
bulk water, not influenced by the solute. It is also
possible to distinguish inside the biological water,
between bound and not-bound molecules, referred to the
bonding with the solute molecules.2
The existence of different kinds of water in sugar solution
has been recently evidence by terahertz spectroscopy
results.3 In the present contribution we show the lowfrequency light scattering spectra of glucose and
trehalose aqueous solutions, obtained with interferometric
and dispersive experimental setups. Using the
susceptibility representation of the recorded intensities,
we are able to distinguish two different contributions of
water molecules and to study the dependence of their
amplitude and relaxation time on temperature and sugar
concentration. Experimental and data manipulation
approach are discussed and a physical interpretation of
the estimated parameters is proposed.
1. Lee, S. L.; Debenedetti, P. G.; Errington, J. R.; J. Chem.
Phys., 2005, 122, 204511-10. 2. Nandi, N.; Bagchi, B.; J. Phys.
Chem. B, 1997, 101, 10954 – 10961. 3. Heugen, U.; Schwaab,
G.; Bründermann, M.; Heyden, M.; Yu, X.; Leitner, D. M.;
Havenith, M; PNAS, 2006, 103, 12301 – 12306.
28
However, a parallel increase of H2O2 production was
always observed during the photocatalytic degradation
runs, confirming the positive role of the noble metal in
favouring the photopromoted electron transfer at the
semiconductor oxide - water interface.
Finally, gold deposition on TiO2 caused a marked
increase of the DMPO-OH adduct concentration under
irradiation. However, surface fluorination and gold
deposition did not exhibit synergistic effects in the
photocatalytic production of oxygen active species on the
TiO2 surface: in fact, the amount of DMPO-OH adduct
detected under irradiation of fluorinated Au/TiO2 water
suspensions was lower than that detected with Au/TiO2.
Hydrogen peroxide, produced in relatively high amount
on Au/TiO2, may provide an extra source of •OH radicals,
parallel to water oxidation by valence band holes, by
reacting with conduction band electrons, according to the
surface process: H2O2 + e-CB → •OH + OH−. Such
reaction is expected to be much less probable on the
fluorinated surface, as demonstrated by the higher
relative photostability of H2O2 on F-TiO2 respect to
naked TiO2 [4].
structure. Then, this model has been used for performing
a more detailed investigation adopting a 30-atomic layers
slab and considering different surface coverages and
periodicities. For both the two steps, the adsorption
energetics have been evaluated by taking into account not
only the binding energy but also the interaction and
distortion ones. In this way, it has been possible to
observe that the adsorbate-substrate interaction is bigger
when the molecule adsorbs by the halogen atom than by
the double C=C bond. A nearest and next-nearest
neighbours model has been employed for evaluating the
lateral effects between the CH2CHF molecules and
obtaining the energies in the limit of an isolated adsorbed
molecule, i.e. when the lateral effects are negligible.
Furthermore, the vibrational frequencies of the molecule
have been determined and compared with the
experimental ones: the good agreement between the
calculated and observed values allows to conclude that
the previously formulated model1 provides a good
description for the adsorption of vinyl halides on the
anatase (101) surface.
In addition, the preliminary results obtained from infrared
spectroscopy and quantum-mechanical studies on the
adsorption of CH2CFCl on TiO2 are also presented.
1. Minero, C.; Mariella, G.; Maurino, V.; Vione, D.; Pelizzetti,
E..; Langmuir, 2000, 16, 8964-8972. 2. Haruta, M.; Gold
Bulletin, 2004, 37, 27-36. 3. Mrowetz, M.; Villa, A.; Prati, L.;
Selli, E.; Gold Bulletin, 2007, in press. 4. Mrowetz, M.; Selli, E.;
Physical Chemistry Chemical Physics, 2005, 7, 1100-1102. 5.
Mrowetz, M.; Selli, E.; New Journal of Chemistry, 2006, 30,
108-114.
1. Scaranto, J; Pietropolli Charmet, A.; Stoppa, P.; Giorgianni,
S.; Journal of Molecular Structure, 2005, 62, 213 – 219. 2.
Saunders, V.R.; Dovesi, R.; Roetti C., Orlando, R.; ZicovichWilson, C.M.; Harrison, N.M.; Doll, K.; Civalleri, B.; Bush, I.J.;
D’Arco, P.; Llunell, M.; CRYSTAL03 User’s Manual, Università
di Torino, Torino (2003). 3. Dovesi, R.; Saunders, V.R.; Roetti
C., Orlando, R.; Zicovich-Wilson, C.M.; Pascale, F.; Civalleri,
B.; Doll, K.; Harrison, N.M.; Bush, I.J.; D’Arco, P.; Llunell, M.;
CRYSTAL06 User’s Manual, Università di Torino, Torino
(2006).
O 2.7
Study on the adsorbate-substrate interaction
between halogenated ethenes and TiO2: IR
spectroscopy
and
quantum-mechanical
calculations.
Jessica Scarantoa, Santi Giorgiannia
a
Università Ca’ Foscari di Venezia, Dorsoduro 2137,
30123, Venezia, [email protected]
The study of the interaction between halogenated ethenes
and TiO2 is very important for the field of the
heterogeneous photocatalysis. In a recent work1 we have
investigated the adsorption at room temperature of vinyl
fluoride and chloride on powdered TiO2 by IR
spectroscopy. On the basis of the experimental data we
have concluded that the adsorption occurs by one
interaction between the halogen atom and the surface
Lewis acid site (Ti4+) and an H-bond between the CH2
group and a surface Lewis basic site.
Here, we present the main results obtained from a
periodic quantum-mechanical study on the vinyl fluoride
adsorbed on the anatase (101) surface. All the
calculations have been performed at DFT/B3LYP level
using the CRYSTAL program2,3. In order to estimate the
slab thickness to adopt for modelling the surface, the
convergence with respect to the structural relaxation and
the surface formation energy has been checked by taking
into account slabs from 6 to 30 atomic layers. The
adsorption study has been subdivided into two main
steps: the first consists in the determination of all the
possible adsorbate-substrate interactions arising from the
adsorption through the halogen atom or the double C=C
bond on a 12-atomic layers slab; this investigation has
allowed to preventively verify that the experimental
model represents an acceptable adsorbate-substrate
29
SEZIONE
COLLOIDI ED INTERFASI
30
relaxation time τ is small on the time-scale 1/γ, aging is
unaffected by the presence of shear. During aging
dynamics slows down, and when τ becomes of the order
of 1/γ, the system enters a shear dominated regime where
aging is strongly reduced and the structural relaxation
time is very sensitive to γ. The intermediate scattering
functions, characterizing the slow non-equilibrium
dynamics of the sheared sample, are well described
assuming an heterogeneous
scenario where the complex dynamics results from the
superposition of relaxing units each one independently
coupled to shear rate.
I3
Aging and flow in a colloidal suspension
Giancarlo Ruocco
Dipartimento di Fisica e CRS SOFT-INFM-CNR,
Università di Roma “La Sapienza”, Piazza Aldo Moro 2,
I-00185, Roma.
Understanding the physical mechanisms governing the
interplay between aging dynamics and shear flow is
crucial to both elucidating the nature of slow dynamics in
soft materials and controlling their complex rheological
behavior.
At the same time we monitor velocity profiles by means
of heterodyne dynamic light scattering.
Shear
localization is observed at the lower rates of shear. An
un-sheared gel band coexists with a uniformly sheared
fluid band whose relaxation time is fixed by the shear
rate.
We investigate the evolution of the density
autocorrelation function of an aging colloidal suspension
subject to a steady shear flow (shear rate γ) . The
competition between the structural relaxation time and
the inverse shear rate gives rise to a complex dynamical
behavior that we could quantitatively analyze studying
the detailed shape of the particles density autocorrelation
function.
We also study the aging process after rejuvenation of the
sample with an high shear rate. The tw dependence of τ
after rejuvenation is substantially different from that
observed in normal aging and follow a power law.
We discuss these results in relation to recent theoretical
work and present a simple phenomenological model
based on Langevin dynamics which is capable of
reproducing many of the observed features.
0 1 2 3 4 0,0
0,5
1,0
1,5
10 100
t w (h) t w (s)
Figure 2. Complete rejuvenation of the Laponite sample
in the slow aging regime, i.e. before gelation. Average
slow relaxation time <τs> is plotted as a function of
waiting time tw for a sample aging soon after filtration
(empty circles) and for the same sample aging after the
application of a shear rate of 100 s-1 for 2 minutes, 13.4
hours after filtration (full circles). Tw is shifted in order to
superimpose the first <τs> measured after the application
of shear with the first aging curve (empty circles). The
black line is a guide for the eye. In the inset the fast
relaxation time is plotted as a function of tw for the two
aging evolution with the same shift in tw. The slow aging
regime is also compared to the fast aging regime, which
is observed after the shear rejuvenation of a gelled
sample: white diamonds represent the evolution of the
slow relaxation time after a shear rate γ = 0.5 s-1, while
grey diamonds are for γ= 100 s-1 (from [2]).
Figure 1. Average slow relaxation time <τs> and
stretching exponent β as a function of waiting time tw
during aging under
different shear rates γ=446 (triangles), 223 (circles), 67
(diamonds), 22 (squares) s-1. Solid symbols refer to aging
without shear. Arrows in top frame indicate the γ -1 values
corresponding to each curve. Inset in top frame shows the
same data in a double-logarithmic scale (from [1]).
The sample is an aqueous suspension of Laponite, a
highly thixotropic liquid which undergoes structural
arrest on a timescale which strongly depends on
concentration and ionic strength and that can be as long
as few months. We found that the aging dynamics
displays two different regimes whose boundary is marked
by the condition τγ=1. As long as the characteristic
1. “Aging under shear: structural relaxation of a non-Newtonian
fluid.” R. Di Leonardo, F. Ianni, and G. Ruocco. Physical
Review E71, 011505 (2005).
2. “Aging after shear rejuvanation in a soft glassy colloidal
suspension: evidence for two different regimes. “ F. Ianni, R. Di
Leonardo, S. Gentilini, and G. Ruocco. Physical Review E75,
011408 (2007).
31
O 3.1
O 3.2
Addressable DNA architectures anchored to
Supported Lipid Bilayers
Structural Stability Against Disintegration by
Anionic Lipids Rationalizes the Efficiency of
Cationic Liposome/DNA Complexes
G. Caminati a, F. Gambinossi a, D. Berti a, M. Banchelli a,
P. Baglioni a, T. Brown b, B. Norden c
a
Department of Chemistry and CSGI – University of
Florence Via della Lastruccia 3, I-50019 Sesto
Fiorentino (FI) Italy
b
School of Chemistry, University of Southampton,
Highfield, Southampton SO17 1BJ, UK
c
Department of Chemical and Biological Engineering /
Physical Chemistry, Chalmers University of Technology,
SE-41296 Gothenburg, Sweden
Giulio Caracciolo,a Daniela Pozzi,a Ruggero Caminiti,a
Cristina Marchini,b Maura Montani,b Augusto Amici,b
Heinz Amenitschc
a
Department of Chemistry, University of Rome “La
Sapienza”, P.le A. Moro 5, 00185 Rome, Italy.
b
Genetic Immunization Laboratory, Department of
Molecular Cellular and Animal Biology, University of
Camerino, Via Camerini 5, 62032 Camerino (MC), Italy.
c
Institute of Biophysics and Nanosystems Research,
Austrian Academy of Sciences, Schmiedelstrasse 6, A8042 Graz, Austria.
The quest for miniaturized arrays of addressable
molecular structure has ignited the use of DNA sequences
as building blocks for increasingly smaller self-assembly
with molecular recognition properties1. Controlled
immobilization of such nanostructures represents an
additional bonus for many applications when tuning of
surface density and directionality is required. Large
spacing between immobilized upright DNA single strands
is still a challenge in the search for efficient hybridization
and
surface-assisted
construction
of
larger
oligonucleotide (ON) architectures2. This issue was
addressed using Supported Lipid Bilayer (SLB) as
scaffold for cholesterol-oligonucleotide insertion. SLBs
form a fluid two-dimensional space allowing free
diffusion and rotation of lipid molecules and lipidassociated molecules directing the hybridization process.
SLBs
of
Palmitoyl-2-Oleoyl-sn-Glycero-3Phosphocholine (POPC) were prepared on gold surfaces
by disruption of POPC liposomes.
The anchoring of cholesterol-TEG-DNA-18mers in the
SLB was followed by means of a dissipative Quartz
Crystal Microbalance (QCM) as a function of time and
ON concentration. Insertion was studied both for the
single- and the double-stranded oligonucleotide as a
function of temperature. QCM data analysis provided the
viscoelastic properties and the thickness of the resulting
architectures whereas temperature cycling evidenced dsONs denaturation at the interface.
SLBs decorated with ds-ONs were also prepared by
direct spreading of POPC vesicles hosting the desired
cholesterol-ON. Excitation dependent emission of
fluorescein covalently attached to the 5’ terminus of one
strand was used to trace the distribution of the ds–ON in
the SLB matrix using spatially resolved Confocal Laser
Scanning Microscopy (CLSM) with Dual Channel
imaging.
Atomic Force Microscopy (AFM) revealed the
morphology and the nanoscale organization of the DNA
construct.
Non-viral gene delivery strategies have been receiving
much attention since the ground-breaking studies by
Felgner et al.1 that had shown how complexes composed
of cationic liposomes (CLs; self-closed lipid vesicles
made of cationic and neutral lipids) and DNA, named
lipoplexes, could serve as gene delivery vehicles in the
targeting of extracellular DNA into cell nuclei. As with
most synthetic transfection systems, the use of lipoplexes
is limited by our insufficient understanding of formation
mechanism, the structure, and the stability of the
complexes and, most importantly, of the manner in which
they cross cell membranes and how they are relieved of
their genetic freight.2
More recently, the unbinding of DNA from a lipoplex
after entering the cell, has been identified as one of the
key steps in lipid-mediated DNA delivery (lipofection).3
A number of investigators observed the release of DNA
molecules from various lipoplexes after treatment with
anionic lipids (ALs).4-6 Experiments have clarified that
the unbinding is a result of charge neutralization by
cellular anionic lipids5,7 and have also suggested that
structural changes of lipoplexes may be a controlling
factor in DNA delivery.3
To test this idea, we investigated the correlation between
transfection efficiency (TE) and structural evolution of
lipoplexes upon interaction with cellular (anionic) lipids.
To this end, we used both binary and multicomponent
(MC) lipoplexes.8,9 MC lipoplexes, incorporating from
three to six lipid species simultaneously, presented much
higher transfection efficiency than binary lipoplexes,
which are more commonly used for gene delivery
purposes.8,9 We applied small angle synchrotron X-ray
diffraction (SAXD) to study the structural correlates of
the lipoplex formulations and their mixtures with anionic
lipids. Electrophoresis experiments were carried out to
measure the extent of DNA unbinding.
We found evidence of the existence of three different
regimes of stability related to interaction between
complexes and anionic membranes. Both unstable (with
low membrane charge density, σM) and highly stable
lipoplexes (with high σM) exhibited low transfection
efficiency while highly efficient multicomponent
lipoplexes exhibited an ‘optimal stability’. This
intermediate regime reflects a compromise between two
opposing constraints: protection of DNA in the cytosol
and endosomal escape. Here we advance the concept that
structural stability, upon interaction with cellular anionic
lipids, is a key factor governing transfection efficiency of
lipoplexes.10
Our results provide a physical basis for rational design of
novel cationic lipid formulations. Future work will be
made to confirm this hypothesis, and to check whether
other effects, such as the specificity of lipid formulations
and cell lines, may play a role in lipid-mediated gene
1. Feldkamp U.; Niemeyer C.M.; Angew. Chem. Int. Ed., 2006,
45 1856.
2. Opdhal A.;. Petrovyckh D.Y; Kimura-Suda H.; Tarlov M.J.;
Whitman L.J.; PNAS, 2007, 104 9.
32
delivery. The future adoption of rationally designed
lipoplexes offering protection against disintegration by
anionic lipids would ensure that users definitely improve
transfection efficiency of lipid carriers.
We studied the solubilization of α,ω-dichloroalkanes in
new aqueous nanostructured media which are composed
of
poly(ethylene
oxide)-poly(propylene
oxide)poly(ethylene oxide) triblock copolymers (PEO-PPOPEO). The thermodynamic study [1] allowed to
determine the oil affinity to the aggregates through the
evaluation of the standard free energy (∆G°) and the
volume (∆V) for the oil-copolymer mixed aggregates
formation. Fluorescence, SANS and DLS experiments [2]
showed that even very low oil amounts added to unimeric
copolymer solution lead to the formation of
oil/copolymer mixed aggregates with a copolymer
aggregation number which increases rapidly with the oil
volume fraction. The oil enhancement of the aggregation
process is less pronounced by decreasing the copolymer
molecular weight.
Figure1. Proposed mechanism of interaction of lipoplexes with
the anionic plasma membrane of the cell. Electrostatic
attractions let the lipoplex approach the anionic surface of the
cell and attachment is followed by endocytosis resulting in
endosomal entrapment. Solid grey line represents a portion of
the plasma membrane separating inner and outer space of a cell.
The less stable the lipoplexes the early the dissociation of DNA
in the cytoplasm (A). When naked, DNA may be easily digested
by enzymes the cytoplasm is rich in. Optimally stable lipoplexes
(B) may release delivered DNA slowly in the cytoplasm, the
event occurring through interactions with anionic proteins which
readily form complexes with cationic vesicles. Too stable
lipoplexes (C) do not fuse with the endosomes and do not allow
for DNA release. Endosomal entrapment therefore results in a
decrease in transfection efficiency.
1. De Lisi, R.; Lazzara, G.; Milioto, S.; Muratore, N.; Journal
Coll. Interface Sci., 2006, 300, 368. 2. Lazzara, G.; Milioto, S.;
Gradzielski, M.: Phys. Chem. Chem. Phys., 2006, 8, 2299.
O 3.4
Orientational order properties of nematic and
smectic B phases of fluorinated liquid crystals
by means of 13C NMR, optical and dielectric
studies
1. Felgner, P. L.; Ringold, G. M. Nature 1989, 331, 461-462.
2. Ewert, K. K.; Ahmad, A.; Evans, H. M.; Safinya, C. R.
Expert. Opin. Biol. Ther. 2005, 5, 33-53.
3. Koynova, R.; Wang, L.; Tarahovsky, Y.; MacDonald, R. C.
Bioconjug. Chem. 2005, 16, 1335-1339.
4. MacDonald, R. C.; Ashley, G. W.; Shida, M. M.;
Rakhmanova, V. A.; Tarahovsky, Y. S.; Pantazatos, D. P.;
Kennedy, M. T.; Pozharski, E. V.; Baker, K. A.; Jones, R. D.;
Rosenzweig, H. S.; Choi, K. L.; Qiu, R. Z.; McIntosh, T. J.
Biophys. J. 1999, 77, 2612-2629.
5. Xu, Y. H.; Szoka, F. C. Biochemistry 1996, 35, 5616-5623.
6. Tarahovsky, Y.; Koynova, R.; MacDonald, R. C. Biophys. J.
2004, 87, 1054-1064.
7. Caracciolo, G.; Pozzi, D.; Caminiti, R., Marchini, C.;
Montani, M; Amici, A.; Amenitsch, H. Appl. Phys. Lett. 2006,
89, 233903-3.
8. Caracciolo, G.; Pozzi, D.; Amenitsch, H.; Caminiti, R.
Langmuir 2005, 21, 11582-11587.
9. Caracciolo, G.; Pozzi, D.; Caminiti, R.; Amenitsch, H. Appl.
Phys. Lett. 2005, 87, 133901-3.
10. Caracciolo, G.; Marchini, C.; Pozzi, D.; Caminiti, R.,
Amenitsch, H.; Montani, M; Amici, A. Langmuir 2007, 23,
4498-4508.
Alberto Marini1,2, Marco Geppi1, Carlo Alberto
Veracini1, Stanisław Urban3, Joanna Czub3, Roman
Dąbrowski4 and Wojciech Kuczyński5
1
Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via Risorgimento 35, 56126 Pisa,
Italy
2
Scuola Normale Superiore di Pisa, Piazza dei Cavalieri
12, 56126 Pisa, Italy
3
Institute of Physics, Jagiellonian University, Reymonta
4, 30-059 Kraków, Poland
4
Institute of Chemistry, Military University of
Technology, 00-908 Warszawa, Poland
5
Institute of Molecular Physics, Polish Academy of
Sciences, Poznań, Poland
In the past few years, liquid crystals displays (LCDs)
have become a nearly inseparable part of our daily life. In
this field fluorinated liquid crystals (FLC) represent an
important class of materials with possible applications,
especially thanks to their broad nematic mesophase
ranges, low rotational viscosity and high dielectric
anisotropy1.
Structural and orientational order properties of
3Cy2CyBF2
[Cr-34.8°C-N-103.2°C-I]
and
of
5CyCy2BF2 [Cr-25°C-SmB-73.3°C-N-121.3°C-I] have
been investigated by means of 13C NMR, optical and
dielectric spectroscopy methods.
O 3.3
Aggregation of triblock copolymers in water
induced by chlorinated oils.
De Lisi R.a, Gradzielski M.b, Lazzara G.a, Milioto S.a,
Muratore N. a, Prevost S.b,c
a
Dipartimento di Chimica Fisica “F. Accascina”,
Università degli Studi di Palermo, Viale delle Scienze,
Parco D'Orleans II, 90128 Palermo, Italy,
[email protected].
b
Stranski Laboratorium für Physikalische und
Theoretische Chemie, Technische Universität Berlin,
Straße des 17. Juni 112, 10623 Berlin, Germany.
c
Hahn-Meitner-Institut Berlin, Glienicker Strasse 100,
14109 Berlin, Germany.
F
H7C3
F
CH2CH2
3Cy2CyBF2
F
H11C5
CH2CH2
5CyCy2BF2
33
F
For both compounds 13C-{1H} NMR static spectra have
been recorded by means of the Linear-Ramped CrossPolarization technique, under SPINAL-64 decoupling2.
The assignment of the 13C resonances have been carried
out thanks to the comparison with solution state spectra
and with DFT calculations using Gaussian’033. From the
NMR point of view, the order parameters have been
calculated analyzing all the 19F-13C dipolar couplings
(DC-F) by means of a least-square fitting procedure,
according to the procedure described in ref. 4. The order
parameters have been also obtained by fitting of all the
experimental 13C chemical shift anisotropies. Dielectric
measurements were performed in a broad frequency
range for two orientations of the nematic director with
respect to the measuring field. At low frequencies a
positive dielectric anisotropy (∆ε) was determined, which
enabled the calculation of the order parameter4. At high
frequencies the ∆ε changes its sign which can be useful in
designing a dual addressing display. The optical
birefringence ∆n = ne – no was measured as a function of
temperature which yielded the order parameter4. The
nematic order parameter determined from the above cited
techniques have been compared. The results so obtained
have been discussed, also with reference to those
previously reported for different fluorinated nematogens4.
absorption (a.u.)
Besides, in the ferritic oxides MeFe2O4, where Me is a
divalent cation, a further variant is given by the
distribution of the cations in the tetrahedral and
octahedral sites of the close packed oxygen structure, as it
may affect the alignment of the moments of the various
ions. The cation distributions are usually expressed in
terms of the so-called inversion degree (γ), defined as the
fraction of divalent ions in octahedral sites.6
In this communication two samples of CoFe2O4
nanoparticles dispersed in silica matrix with different
abundance (10% and 5% by weight of CoFe2O4, called
N10 and N5 respectively) and same mean particle size
(~3 nm) are presented. Under these conditions the
particle size effects should be similar in the two samples
and this would make it possible to undertake a finer study
of effects due to other factors. The magnetic properties of
the nanoparticles are investigated through the combined
use of classic magnetometry (AC and DC measurements)
and Mössbauer spectroscopy (in zero and in high
magnetic field).
In both samples the interparticle interactions are
very weak, but through the combined use of Mössbauer
spectrosocpy and magnetic measurements (ZFC-FC,
TRM) some differences are highlighted.
1. Kirsch, P.; Bremer, M.; Angew. Chem. Int. Ed., 39, 4216,
2000.
2. Fung, B. M.; Khitrin, A. K.; Ermolaev, K.; J. Magn. Reson.
142, 97, 2000.
3. Gaussian 03, Revision B.05. M.J. Frisch et al., Gaussian, Inc.,
Pittsburgh PA, 2003.
4. Catalano, D.; Geppi, M.; Marini, A.; Veracini, C. A.; Urban,
S.; Czub, J.; Kuczynski, W.; Dabrowski, R.; J. Phys. Chem. C,
111, 5286, 2007.
N5
N10
-10
O 3.5
-5
0
Velocity (mm/s)
5
10
Despite the particles in the two samples have
the same size, they show different values of saturation
magnetization (Ms) and coercive field. In addition Ms is,
for both samples, higher than the bulk value. From
Mössbauer spectra in a magnetic field of 6T at low
temperatures, 6K, (figure) the degree of spin-canting and
the cationic distribution can be estimated. The best fit
was obtained with three sextet assuming that some of the
iron atoms are in perfect ferrimagnetic local
environments and in accordance with this the relative
areas of lines 2 and 5 were constrained to zero for two
sextets corresponding to A (sextet 1, Fe3+ tetrahedrally
coordinated) and B sites (sextet 2, Fe3+ octahedrally
coordinated). A third sextet (sextet 3) was introduced to
represent ions with canted spins, and in this component
the ratio between the areas of the lines 2,5 and 3,4 was
free. In all the three sextets the line widths and line
intensities were constrained to be pair-wise equal.7,8 In
both samples, sextet 2 and sextet 3 show values of isomer
shifts typical for octahedrally coordinated Fe3+ in spinel
but larger than that of sextet 1, which is typical for
tetrahedrally coordinated Fe3+. This indicates that the
canted spins are mainly located in the B sites.7
In the table, the values of the saturation
the
magnetization (Ms), the inversion degree (γ),
anisotropy constant (K) and percentage of canted spins
(Nc) for both samples are reported.
Magnetic
properties
of
ultra-small
nanoparticles: beyond the influence of particle
size
D. Peddisa, C. Cannasa, D. Fioranib, A. Musinua, G.
Piccalugaa, S. Mørupc
a
Dipartimento di Scienze Chimiche, Cittadella
Universitaria di Monserrato, bivio per Sestu, 09042
Monserrato (Cagliari), Italy. [email protected]
b
Istituto di Struttura della Materia-CNR. C.P. 10, 00016
Monterotondo Stazione (Roma), Italy.
c
Department of Physics, Technical University of
Denmark, DK-2800 Kongens Lyngby, Denmark
The magnetic properties of nanosized particles
are a subject of great interest both for application
purposes (information storage,1 ferrofluid technology,2
biomedical application3) and for basic research to
investigate, for example, how bulk properties transform
as the size is decreased.4 In this framework a lot of work
has been focused on the study of the dependence of
magnetic properties on particle size. Anyway, this
approach is not completely exhaustive, because other
factors affect the magnetic behaviour of nanoparticles.
Magnetic interactions among nanoparticles play an
important role in the physics of these system as well as
the magnetic structure. The presence of non-collinear
(canted) spin structures leads to modifications of the
magnetic properties and for this reason “spin canting”
may be, in some cases, a key point to understand the
magnetic behaviour of nanoparticles.5
N5
N10
34
Ms
(A m2 Kg-1)
109 (2)
89(2)
γ
0.22(2)
0.44(4)
Nc
(%)
23 (3)
17 (3)
K
(J/m3)
1.7×106
1.6×106
Both samples show a considerable fraction of canted
spins, highest in the more diluted nanocomposite. The
magnetic anisotropy constants are much larger than that
of bigger particles (> 7 nm),7 presumably because of a
large surface contribution to the anisotropy. A low
inversion degree compared to bulk samples (γ bulk ~ 0.5)
and other CoFe2O4 particles is observed. 9 This can be
correlated with the surprisingly high values of saturation
magnetization, especially for N5 nanocomposite.
In conclusion, using magnetometry and Mössbauer
spectroscopy in high magnetic field, a careful study of
magnetic structure of nanoparticles has been performed
and this allows explaining the difference in magnetic
properties of the samples that do not depend on particle
size.
Na-A
0.2 a.u.
Na-Y
0.4 a.u.
Na-ZSM-5
1. Matsui, I.; J. Chem. Eng. Jpn., 2005, 38, 535. 2. Rosensweig,
R. E.; Chem. Eng. Prog., 1989, 85, 53. 3. Tartaj, P.; Morales,
M.P.; Vientemillas-Verdaguer, S.; Gonzales Cárreño, T.; Serna,
C.J.; J. Phys. D, 2003, 36, R182. 4. Dormann, J.L.; Fiorani, D.;
Tronc E.; Advances in Chemical Physics, Wiley, New York,
1997, Vol. XCVIII, p. 283. 5. Coey, J.M.D.; Phys. Rev. Lett.,
1971, 27, 1140. 6. West, A.R.; Solid State Chemistry, Eds. Wiley
&Sons. New York, 1984. 7. Cannas, C.; Musinu, A.; Piccaluga,
G.; Fiorani, D.; Peddis, D.; Rasmussen, H.K.; Mørup, S.; J.
Chem. Phys., 2006, 125, 16, 164714. 8. Anhøj, T.A.; Bilenberg,
B; Thomsen, B.; Damsgaard, C.D.; Rasmussen, H.K.; Jacobsen,
C.S.; Mygind, J.; Mørup S.; J. Magn. Magn. Mater., 2003, 260,
115. 9. Sawatzky, G.A.; Van der Woude, F.; Morrish, A.H.;
Phys. Rev., 1969, 187, 747
0.2 a.u.
Silicalite
0.02 a.u.
4160
4140
4120
4100
4080
4060
-1
Wavenumber (cm )
From top to the bottom: IR spectra of H2 adsorbed at
20 K on NaA, NaY, Na-ZSM-5 and silicalite (the
different curves correspond to increasing filling
conditions).
O 3.6
Computational and spectroscopic screening of
microporous materials for molecular hydrogen
storage
addressed the theoretical description of adsorption on
metal organic frameworks (MOFs), with careful analysis
of the binding of H2 to both the inorganic and organic
sites of the structure [5]. The correct description of long
range dispersive interactions, accounting for a significant
fraction of the binding energy in microporous materials
has stimulated the development of a nover molecular
mechanics forcefield for MM simulations, obtained by
fitting the ab-initio PES for the H2-H2 system and the
eperimental dipole polarizability and quadrupole moment
of the H2 molecule [6]. Finally, the problem of the
maximal storage capacity of porous materials has been
addressed using atomistic molecular dynamics
simulations A method is devised for the prediction of the
maximal capacity of a given microporous crystalline
framework, and the method is applied to a variety of
frameworks[7]. The obtained maximum capacities for
zeolites are approximately 2.5% wt., well below the
targets for mobile applications.
The interaction of H2 with zeolite frameworks of variable
polarity, topology and chemical composition, with
several metal-organic framework, and with different
porous polymers has been studied with low temperature
IR experiments, which allow the measurement of heats of
adsorption on specific sites, and with volumetric
adsorption experiments [5,8,]. Low interaction energies
are found in all cases (3-10 kJ/mol), in agreement with
our calculations. However, calculations and experiments
allow to highlight the desirable features, at the atomic
scale, for better hydrogen adsorbers. In conclusion, the
combined use of spectroscopic and theoretical methods
allows a relatively fast and reliable screening of materials
for their hydrogen storage potential, and provides
guidelines for the functionalization of known porous
structures with active sites with high hydrogen affinity.
Gabriele Ricchiardi, Jenny G. Vitillo, Giuseppe Spoto,
Silvia Bordiga and Adriano Zecchina
Dipartimento di chimica IFM and Centro di Eccellenza
NIS, Università di Torino, Via P. Giuria 7, 10125
TORINO, Italy, e-mail [email protected]
Hydrogen storage by physisorption of molecular H2 is a
widely investigated option, and several classes of
materials have been studied [1]. Among these, crystalline
microporous materials like zeolites and metal organic
frameworks, as well as several carbon structures, porous
polymers and clathrates. Since several years we have
addressed the problem of determining the nature and
strength of the interactions of molecular H2 with
microporous materials by means of computational and
spectroscopic techniques, aiming at understanding the
key interactions involved and thus enabling an efficient
screening of novel proposed materials for hydrogen
storage, and the design of optimized adsorbents.
The interaction of H2 with isolated cations, anions, and
ion pairs modeling the adsorption sites of zeolites has
been studied with accurate quantum methods (compared
with a large set literature data) [2,3]. Relationships
between the binding energies to anions and cations and
the vibrational frequency of the molecule are determined,
which show its peculiar nature as a “probe molecule”
responding to polarizing fields of both signs. A
breakdown of the interaction energies into its electrostatic
and dispersion components is also obtained. This
theoretical analysis has been extended to cations
embedded in zeolite frameworks [4], in order to evaluate
the strategy of functionalizing less-polar materials with
polarizing ions. Giving the intrinsic limitations of zeolites
ad hydrogen storage materials (see below), we have then
35
1.
2.
3.
4.
5.
6.
7.
8.
showing a considerable enhancement in light extraction3,4
(Fig.1).
A.Zuettel, Naturwissenschaften 91 (4): 157-172,
2004
Vitillo JG, Damin A, Zecchina A, Ricchiardi G,
J.Chem.Phys. 122 (11): Art. No. 114311 2005
Vitillo JG, Damin A, Zecchina A, Ricchiardi G,
J.Chem.Phys. 124 (22): Art. No. 224308, 2006
Torres FJ, Vitillo JG, Civalleri B, Ricchiardi G,
Zecchina A , J.Phys.Chem.C 111 (6): 2505-2513,
2007
Bordiga S, Vitillo JG, Ricchiardi G, J.Phys.Chem.B,
109 (39): 18237-18242, 2005
Gabriele Ricchiardi, Jenny G. Vitillo, Donato
Cocina, Evgueni N. Gribov and Adriano Zecchina
Phys.
Chem.
Chem.
Phys.,
2007,
DOI:
10.1039/b703409a
Vitillo JG, Ricchiardi G, Spoto G, Zecchina A,
PCCP, 7 (23): 3948-3954 2005
Zecchina A, Bordiga S, Vitillo JG, Ricchiardi G,
Lamberti C, Spoto G, Bjorgen M, Lillerud KP,
J.Am.Chem.Soc., 127 (17): 6361-6366 2005
Fig.1:
II-VI semiconductor nanocrystals in
functionalized PMMA based co-polymers: highly
homogeneous and luminescent composites for Nano
Imprinting Lithography
The obtained results confirm the potential of the prepared
luminescent functional materials for micro and nano
fabrication, thus envisioning their development in
permanent photonic applications.
Acknowledgments:
O 3.7
The support of the EC-funded project NaPa (contract no. NMP4CT-2003-500120) and of MIUR Italian National Project no.232
is gratefully acknowledged. The content of this work is the sole
responsibility of the authors.
References:
Luminescent Nanocrystals in PMMA Based Copolymers: Novel Nanocomposite Materials for
Nano Imprint Lithography.
1 M. Tamborra, M. Striccoli, M. L. Curri, A. Agostiano “Hybrid
Nanocomposites Based on Luminescent Colloidal Nanocrystals
in PMMA: a Spectroscopical and Morphological Investigation”
Journal of Nanoscience and Nanotechnnology (2007) in press.
Michela Tamborra1,2, Maria Lucia Curri1, David
Mecerreyes3, Juan Antonio Alduncin3, Josè Adolfo
Pomposo3, Nikolaos Kehagias4, Vincent Rebaud4, Clivia
M. Sotomayor Torres4, Marinella Striccoli1*
2 M. Tamborra,, M. Striccoli, M. L. Curri, J. A. Alducin, D.
Mecerreyes, J. A. Pomposo, N. Kehagias, V. Reboud, C. M.
Sotomayor Torres, A. Agostiano “Nanocrystal-Based
Luminescent Composites for Nanoimprinting Lithography”
Small vol.3, Issue 5, pag.822-828 (2007)
1
IPCF, CNR, c/o Dept. Chemistry, University of Bari,
Italy;
2
Department of Chemistry, University of Bari, Via
Orabona 4, 70126 Bari, Italy;
3
CIDETEC, San Sebastian, Spain;
4
Tyndall National Institute, University College Cork, Lee
Maltings, Cork, Ireland.
3 V. Reboud, N. Kehagias, M. Zelsmann, M. Striccoli, M.
Tamborra, M. L. Curri, A. Agostiano, M. Fink, F. Reuther, G.
Gruetzner, C. M. Sotomayor Torres “Spontaneous emission
control of colloidal nanocrystals using nanoimprinted photonic
crystals” Appl. Phys. Lett. 2007, 90, 011115 selected for
publication on the January 22, 2007 issue of Virtual Journal of
Nanoscale Science &Technology.
The design of new functional materials, able to join novel
tailored physical and chemical properties with versatile
and reliable processing capabilities, represents one of the
most crucial challenges in modern material science. In
this view, nanocomposite materials, based on
thermoplastic polymers functionalized with inorganic
nanoparticles, convey the unique size-dependent
properties of nanosized particles into highly processable
polymers.1 The prepared materials then exhibit
extraordinary optical and magnetic properties, as well as
catalytic activity and mechanical strength. At the same
time these functional materials are suitable for innovative
fabrication process at micro and nano scale. Here the
preparation of nanocomposites based on the incorporation
of pre-synthesized CdSe@ZnS core-shell luminescent
nanocrystals both in a curing resist polymer and into
properly
functionalized
PMMA
(poly-methyl
methacrylate) co-polymers, is presented2,3. The
spectroscopic and structural characteristics of the
prepared materials are investigated in terms of chemical
and physical interactions between the composite moieties
to evaluate the nanocrystal interactions with the host
matrix. In addition the well known excellent
processability of both polymer matrixes in high
resolution lithography has been exploited. Here, the
fabrication of 2-D patterned photonic structures by
Nanoimprint Lithography (NIL) has been demonstrated,
4 V. Reboud, N. Kehagias, M. Zelsmann, M. Striccoli, M.
Tamborra, M.L. Curri, A.Agostiano, D.Mecerreyes, J.A.
Alduncín, C.M.S. Torres “Nanoimprinted photonic crystals for
the modification of the (CdSe)ZnS nanocrystals light emission”,
Microelectronic
Engineering
(2007)
in
press
doi:10.1016/j.mee.2007.01.201.
36
SEZIONE
CHIMICA FISICA DEI MATERIALI
37
I4
O 4.1
Carbon Based Electron Donor Acceptor Hybrids
for Solar Energy Conversion
Stato dell’arte e Potenzialità del Solare Termico
Antonio Bee
COSTRUZIONI SOLARI, Zona PIP Cavallino, Lecce,
c.s@ costruzionisolari.it
Dirk M. Guldi
Institute for Physical Chemistry, University of Erlangen,
91058 Erlangen; e-mail: [email protected]
I pannelli solari piani, attualmente utilizzati, trasformano
l’energia solare diretta e diffusa in calore. Questa
tecnologia ha una buona efficienza per temperature fino
agli 80° C. Ciò permette di coprire in modo efficace, una
larga fascia di utilizzi: acqua calda sanitaria ad uso
domestico e collettivo (alberghi, ospedali, ecc..),
riscaldamento dell’acqua di piscine, riscaldamento
d’ambiente (appartamenti, scuole, fabbriche), utilizzo del
calore come acqua di processo nel settore industriale per
temperature fino a 80°C.
La sfida che invece ci sta coinvolgendo ora e per i
prossimi anni, è quella di ottenere tramite l’utilizzo del
calore altre prestazioni oggi negate ai pannelli solari
piani.
Lo studio che stiamo effettuando si sviluppa su alcuni tipi
di macchine che devono lavorare con elevata efficienza a
temperature costanti di 100°C, 250°C, 600°C.
Il raggiungimento dei 100°C dà la possibilità di utilizzare
il calore prodotto dai pannelli solari nei gruppi frigoriferi
ad assorbimento a bromuro di litio per generare freddo da
utilizzare sia nel settore industriale che civile. Le
macchine solari (paraboloidi non focalizzanti) che
devono lavorare a temperature di 250°C servono per la
produzione di vapore da utilizzare nel settore
dell’industria alimentare e industriale. Infine le macchine
che devono lavorare a temperature di 600°C servono per
la produzione di energia elettrica mediante turbine;
l’energia così prodotta può essere utilizzata anche per la
produzione di idrogeno mediante il processo elettrolitico;
questa è una delle vie più interessanti per la
conservazione dell’elevatissima quantità di energia solare
del periodo estivo, in tal modo è possibile utilizzarla in
tutti i periodi dell’anno.
Carbon-based nanomaterials are currently under active
investigations for producing innovative materials,
composites, and electronic devices of greatly reduced
size. Among the wide variety of carbon materials (i.e.
fullerene, single and multi wall carbon nanotubes, carbon
fibers, carbon nanoonions, and single wall carbon
nanohorns), single wall carbon nanotubes (SWNT) and
single wall carbon nanohorns (SWNH) are of particular
interest.
The structure of SWNT is conceptualized by wrapping a
one-atom-thick layer of a graphene sheet, that is, an
interlinked hexagonal lattice of carbon atoms, into a
seamless cylinder. The diameter of most SWNT is close
to 1 nm, with a tube length that might be many thousands
of times larger.
Importantly, based on different
arrangements, SWNT possess different electrical
properties (i.e., semiconductor or metallic), which are the
result of the electrons moving differently in the tube
depending on the SWNT arrangement.
SWNH, on the other hand, are typically constituted by
tubes of about 2-5 nm of diameter and 30 to 50 nm long,
which associate with each other to give rise to roundshaped aggregates of 100 nm of diameter. SWNH are
easily produced in large-scale quantities (i.e., up to 50
g/h) with an extraordinary purity (>90%) and, most
importantly, are free of metal residue, since they are
produced in the absence of any metal catalysts. Their
large surface areas (1006-1464 m2g-1) and inner
nanospaces (0.47-1.05 mL/g) are of great importance,
since they ensure a great affinity with organic electron
donors and make them promising candidates for electrical
and chemical solar energy conversion.
In this respect, I will highlight the opportunities that rest
on carbon nanostructures – much beyond the well-studied
fullerenes – within the context of electron transfer
reactions in novel chemical and light driven systems. In
particular, I will survey our approaches to design,
characterize, and examine the potential for practical
applications of super- and supramolecular association of
carbon-based nanomaterials with electron donors towards
stable donor-acceptor nanohybrids and nanoconjugates
within the context of light induced charge separation and
solar energy conversion. Important are the impact, the
benefits and some of the promises that evolve from
electron transfer reactions with carbon nanostructures on
i) the stabilization of radical ion pair states, ii) multi
electron catalytic reactions and iii) photoelectrochemical /
photovoltaic solar energy conversion.
O 4.2
Role of defects and defect interactions on the
photovoltaic properties of solar grade silicon
S. Binetti, M. Acciarri, J.Libal
Dipartimento di Scienza dei Materiali, Università
di Milano-Bicocca, via Cozzi 53, I-20125 Milano,
Italy [email protected]
Nowadays silicon covers, as single crystal,
multicrystalline (mc) almost the 90% of the photovoltaic
(PV) market.
Currently the only commercial source for solar grade
silicon (SoG-Si) is rejected and no-prime silicon from the
semiconductor industry, but at the moment the shortage
of Solar grade silicon is leading to high prices and a new
supply of SoG-Si at reasonable costs is crucial for PV
industry development.
One of the possible solutions is to produce SoG- silicon
via a direct metallurgical route, followed by purification
processes and by a final casting step to get
multicrystalline (mc) silicon wafers. The material today
available is however characterized by an high impurity
content and relevant defectivity
(dislocations,
38
Electronic detection with organic thin-film transistor
(OTFT) sensors results in field-effect amplified responses
repeatable within a standard deviation of few percentages
[1]. Polycrystalline conducting polymers (CP) act both as
transistor channel materials and sensitive layers and the
CP side groups confer broad chemical selectivity but
specificity and high sensitivity are yet open issues. Chiral
discrimination is one of the hardest bench-test to prove
sensors performance particularly in terms of selectivity
and sensitivity. Here a OTFT gas sensor, bearing an
amino-acid substituted CP active layer, is demonstrated
to exhibit amplified sensitivity that allow to selectively
detect β-citronellol enantiomers in the tens part per
million (ppm) concentration range with highly repeatable
responses. Markedly different sensitivities are seen for
(S)- β-citronellol and (R)- β-citronellol and even in a
racemic misture. The semi-conducting oligomers, which
are designed to combine field-effect and enantiomeric
recognition properties, are implemented in a novel
sensing OTFT structure. Alkoxyphenylene-thienylene
conjugated systems have been chosen for the active layer
as they allow to covalently attach a wide variety of
molecules as side groups, including bio-receptors [2-3],
exhibiting also field-effect properties when deposited by
the Langmuir-Schäfer (LS) procedure [4]. Chiral CP were
synthesized already twenty years ago and differential
detection of single enantiomers was performed with
electrochemical, gravimetric and chemiresistor [5,6]
sensors at part per thousand (ppth) concentrations. Our
results demonstrate that combining field-effect amplified
detection with chiral CP recognition properties allows
enantiomeric discrimination at much lower concentration.
This is a significant step further in the development of a
highly-performing nanoscalable electronic sensing
platform fully compatible with fast advancing organic
electronic technologies.
precipitates). So the use of this material in solar cell
production depends on the possibility of improve the
electrical quality during the cell process in order to make
it compatible in terms of solar conversion efficiency.
A deep understanding of the chemical physics of defects
interactions and of the impurities segregation processes is
the basic background needed to develop tools able to
adapt the material to PV applications.
In this work it will be shown that the combined
application of Photoluminescence and Infrared
spectroscopy and Electron Beam induced Current
(E.B.I.C) technique to study the recombination activity
of extended defects in SoG-Si wafers succeeded in the
identification of the nature of the defects which limit the
quality of the base material and of the solar cell In the
low temperature (T=12K) configuration, the PL
technique was specifically adopted here for the study of
SoG-Si multicrystalline ingots grown by the DS
technique, by sampling wafers coming from different
horizontal sections of the ingots, to follow the effect of
impurity segregation at extended defects.
Furthermore, the level of impurity-contamination of
dislocations has been systematically studied by EBIC
contrast measurements at different temperatures. In order
to improve the material quality, the samples have been
also submitted to an ad hoc P-diffusion gettering process.
As expected, the average lifetime increases after the Pdiffusion process, which induces impurity gettering
effects at the external surfaces. An increase of the local
diffusion length was observed in defect-poor defective
regions whereas the gettering efficiency is reduced in
regions characterized by the presence of a high density of
defects. An evident local increase of the electrical activity
of some grain boundaries, after the P-diffusion process,
was also observed. Furthermore, the PL spectroscopy
mapping revealed the presence of as grown and process
induced oxide precipitates. Apparently, a redistribution of
impurities occurs at the processing temperature and
impurities are captured at the deepest sinks. In fact, since
grain boundaries act as heterogeneous segregation/
precipitation sites, some of them will compete with the
external surfaces sinks, partly neutralising the effect of
P-gettering.
This proves that extended defects represent a limiting
factor for high efficiency solar cells but electrical
properties in multicrystalline silicon of different quality
can be improved if an appropriate cell process is applied.
[1] Torsi, L. and Dodabalapur, A. Anal. Chem. 70,
381A (2005).
[2] Babudri, F., Farinola, G.M., Naso, F. J. Mater.
Chem. 14, 11 (2004).
[3] Naso, F., Babudri, F., Colangliuli, D., Farinola,
G.M., Quaranta, F., Rella, R., Tafuro, R., Valli, L.
J. Am. Chem. Soc. 125, 9055 (2003).
[4] Tanese, M.C., Farinola, G.M., Pignataro, B., Valli,
L., Giotta, L., Conoci, S., Lang, P., Colangiuli, D.,
Babudri, F., Naso, F., Sabbatini, L., Zambonin, P.G.,
Torsi, L, Chem. Mat. 18, 778 ( 2006).
[5] Severin, E. J., Sanner, R. D., Doleman, B.J., Lewis,
N.S. Anal. Chem. 70, 1440 (1998).
de Lacy Costello, B.P.J., Ratcliffe, N.M., Sivanand, P.S.
Synth. Met. 139, 43 (2003)
This work has been carried out in the framework of the EUfounded Research Project “FOXY “ (VI Framework Program).
O 4.3
Chiral recognition with enhanced
organic thin-film transistors
O 4.4
sensing
Structural and physico-chemical studies of
innovative layered Al-modified magadiite
materials
L. Torsia,b, G.M. Farinolaa, P. Iliadea, M.C. Tanesea, O.
Hassan Omarc, L. Vallid, G. Giancaned, F. Babudria,c, F.
Palmisanoa, P.G. Zambonina,b and F. Nasoa,c
a
Dipartimento di Chimica Università degli Studi di Bari Bari (Italy);
b
Centro di Eccellenza TIRES - Università degli Studi di
Bari - Bari (Italy);
e
CNR ICCOM, Dipartimento di Chimica - Università degli
Studi di Bari - Bari (Italy);
d
Dipartimento di Ingegneria dell’Innovazione - Università
degli Studi di Lecce - Lecce (Italy);
Chiara Bisioa, Guilherme Supertib, Heloise O. Pastoreb,
Leonardo Marchesea
a
DISTA, Università del Piemonte Orientale “A.
Avogadro”,
15053
Alessandria
(Italy),
[email protected]
b
Instituto de Quimica, Universidade Estadual de
Campinas, Brasil
Introduction
39
and TGA studies, which suggested that, besides
molecular water, silanol groups were eliminated at
temperatures higher than 593K. A progressive collapse of
the magadiite structure, which transforms into a dense
phase, occurred from 723 to 1023 K.
The progressive condensation of silanols and elimination
of water, allowed a coupling between adjacent silica
layers, as suggested by the progressive intensification in
the IR spectra of a specific band at ca. 704 cm-1 with
increasing temperature [3]. Moreover, the silica rings also
appeared irreversibly modified with the temperature
(bands in the 650-500 cm-1). Introduction of Al and
subsequent Na+ exchange with ammonium ions affected
the hydrophilic properties of the materials. Indeed, TGA
analysis showed that NH4-[Al]-magadiite samples
contained a much lower amount of water with respect to
the parent Na-magadiite, as expected from the absence of
Na+ ions in interlamellar position. Decomposition of
exchanged ammonium ions occurred at temperatures
higher than 593K, and Brønsted acid sites were produced,
as monitored by IR spectroscopy of CO adsorbed at 100K
(Fig. 2).
Magadiite is a crystalline hydrated sodium silicate, with
an ideal unit cell of Na2Si14O29xH2O [1], characterized by
a layered structure, in which the negatively charged
silicate layers are compensated by sodium ions. The
crystal structure of magadiite is still unknown as no
single crystals with suitable dimensions has never been
obtained [2].
The intrinsic properties of this material can be exploited
for applications as cation exchanger, adsorbent material,
molecular sieve, catalysts support or polymer additive [35]. Nevertheless, more applications can be found by
insertion of Al in the framework, leading to Brønsted acid
surface centers that may be exploited in catalysis
especially for the possibility to tune the surface
hydrofobicity.
The synthesis strategy of Al-modified magadiite
materials and the effects that such modifications have on
the original surface properties of silicic magadiite will be
illustrated in this work. In addition, details concerning the
siliceous magadiite structure, obtained by combining
experimental synchrotron XRPD and modeling
techniques will be also discussed.
Experimental
Na-magadiite was prepared following procedure
described in the literature [3]. The hydrothermal synthetic
procedure was modified to introduce Al in the siliceous
structure. Al-modified magadiite with different Si/Al
ratio (15, 30 and 60) were then prepared using Alisopropoxide as aluminum source. The so-obtained
Na[Al]-magadiite were then fully-exchanged with NH4+
to prepare a precursor of H[Al]-magadiite. Acid
magadiite samples were finally prepared by decomposing
ammonium at high temperature in vacuum conditions.
Absorbance [a.u.]
0.05
3566
3615
[Al]-magadiite
∆ν = 193
3600
3400
3200
3000
-1
Wavenumber [cm ]
Fig.2: FTIR spectra evolution (in the 38003000 cm-1 range) of CO adsorbed at 100K on
NH4-[Al]-magadiite (Si/Al ratio =15)
IR data suggested that almost three different type of
Brønsted acid sites were present in [Al]-magadiite
samples, especially at higher Al content (see figure). The
comparison with the results obtained on zeolite materials
with similar Si/Al ratio allowed to evidence a higher
heterogeneity of Brønsted acid sites in the case of Almodified magadiite (dotted curve in the figure is related
to a H-MCM-22 sample). The modification of the OH
stretching vibration occurred after CO interaction (∆νOH)
indicates that [Al]-magadiite contains sites whose acidity
is higher than for acid zeolites, being ∆νOH≅ 280- 310 cm1
for Al-OH groups and ∆νOH≅ 365 cm-1 for Si(OH)Al
sites, while ∆νOH values associated to similar sites in
zeolites are 200-220 and 300-320 cm-1, respectively.
These results indicated that the synthesis procedure
allowed to introduce aluminum ions in tetrahedral
coordination within the magadiite silica framework, in
fully agreement with solid state 27Al MAS-NMR studies.
The presence of framework Al ions led to very strong
Brønsted acid sites, which may be relevant for acidcatalyzed reactions.
1000cps
r.t.
Intensity (a.u.)
H-MCM-22
∆ν= 365
3800
A detailed physico-chemical characterization of Namagadiite and Al-derived solids were performed by using
different experimental (XRDP analysis, TGA, IR and SSNMR spectroscopy) and modeling techniques.
Several details on the magadiite structure, obtained by
coupling synchrotron XRPD and computational models,
will be illustrated.
XRD diffraction studies performed at increasing
temperature (from r.t. to 1023 K) on all NH4-[Al]magadiite samples (Fig.1), showed that the thermal
stability of the structure is similar to that of Na+magadiite.
473K
593K
723K
873K
5
/2
3250
∆ν = 280-310
Results and discussion
x 0,2
3422
1023K
10 15 20 25 30 35 40 45 50
2 theta/ degree
Fig.1: XRD pattern at increasing temperature of a
NH4-[Al]-magadiite with Si/Al ratio of 15
References
1 Eugster H.P., Science 157 (1967) 1117- 2. A. Brandt, W.
Schwieger, K.H. Bergk, Rev. Chim. Miner. 24 (1987) 564- 3. C.
Eypert-Blaison,E. Sauzéat, M. Pelletier, L.J. Michot, F. Villiéras
ad B. Humbert, Chem. Mater. 13 (2001) 1480; C. EypertBlaison,E. Sauzéat, M. Pelletier, L.J. Michot, F. Villiéras ad B.
Humbert, Chem. Mater. 13 (2001) 4439- 4. S.T. Wong, S.
Cheng, Chem. Mater. 5 (1993) 770- 5 J. S. Dailey, T. J.
Pinnavaia, Chem. Mater. 4 (1992) 855
It was thus inferred that the introduction of Al ions does
not affect the stability of the silica layers. Strong
modifications of the XRD profiles occurred at T ≥ 473K,
thus indicating that structural changes began at relatively
low temperatures. The interlamellar space varied from
15.5 to 11.8 Å by heating at 473 K, due to desorption of
water molecules. This process was also followed by IR
40
O 4.5
O 4.6
Preparation and optical properties of metal
nanostructures.
Characterisation of highly dispersed gold on
ZrO2 catalysts active in the WGS reaction
Maela Manzolia, Flora Boccuzzia, Anna Chiorinoa,
Floriana Vindignia, Francesco Pinnab, Federica
Menegazzob, Valentina Trevisanb
a
Dipartimento di Chimica I.F.M. and NIS Centre of
Excellence, Via Pietro Giuria 7, 10125 Torino, Italy,
[email protected]
b
Dipartimento di Chimica, Università di Venezia and
Consorzio INSTM UdR Venezia, Venezia, 30123, Italy
Loredana Latterini, Matteo Amelia, Gian Gaetano Aloisi,
Fausto Elisei
Dipartimento di Chimica and CENIM, Università di
Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy;
([email protected])
Hybrid organic-inorganic nanostructures having a defined
morphology and structure controlled at nanometric level
represent a new and interesting class of materials for their
biomimetic features and their versatility in many fields of
high technologies.1 Metal nanostructures have recently
attracted attentions since they turned out to have
interesting optical properties which can be tuned upon
control of synthesis conditions.2 In particular, the main
resonance absorption peak of gold- and silver-spheres is
centered at 520 and 430 nm, respectively and their
spectral position and features are strongly affected by
particle dimensions and shape3 till they reach intense
absorption in the near-infrared region (NIR) by emptying
the interior of spherical nanoparticles to form hollow4 or
preparing Au-Ag alloys.5 Furthermore, nanoshells
convert absorbed light to heat with an efficacy and
stability that far exceeds that of conventional dyes.1
Au and Ag (and their alloys) nanoparticles and
nanoshells have been prepared by use of selective redox
reactions and/or galvanic methods.
The most popular explanation for the variability of the
catalytic properties of gold catalysts focuses on the
amount of low-coordinated gold sites, whose
concentration is usually related to the size of gold
metallic particles.
High resolution transmission electron microscopy
(HRTEM) can provide a particle size distribution from
which a mean size can be obtained, but because of the
hard detection of very small metallic particles (< 1 nm),
this technique is not ideally applicable for samples
containing highly dispersed gold.
In the present work, FTIR measurements of CO adsorbed
at 120 K up to room temperature and quantitative CO
chemisorption in the range 140-180 K were performed
on differently prepared highly dispersed gold supported
on zirconia.
The gold content was about 1 wt % for all samples and
the metal has been loaded on the supports, previously
calcined at 923 K, by deposition-precipitation at pH=8.6
with two different reagents: Na2CO3 and NaOH.
Both fresh and used (after 10 h in the water gas shift
reaction mixture at 453-423) catalysts have been
examined.
The aim was to determine quantitatively the amount of
gold active sites by correlating the moles of chemisorbed
CO with the integrated areas, normalized to the Au
content, of the CO absorption bands on gold.
The results have been compared with those obtained (1)
on the two reference samples provided by the World
Gold Council, 1.51 wt% Au/TiO2 and 4.48 wt%
Au/Fe2O3, and with another low gold content catalyst,
Au/Fe2O3 prepared by NaCN leaching of the parent
sample.
The ratio molCO/molAu (0.32-0.36) and the Iint/ molAu
(2.27-2.84) obtained for the fresh gold samples supported
on zirconia are much larger than those related to the
reference catalysts (0.028-0.033 and 1.05-1.10) indicating
a gold dispersion at an atomic level.
On the contrary, the corresponding used samples showed
analogous spectroscopic features to those of the reference
catalysts, indicating an agglomeration of the metal after
reaction as demonstrated by the appearance of metallic
particles in the HRTEM images.
The statistical analysis of the particles dimensions
obtained by TEM and AFM allowed to optimize the
synthisis conditions to have full control of size and
shaping.
Gold-nanoshell have been prepared upon deposition of
gold clusters on silica dispersion or by galvanic exchange
reactions. The preparation conditions were changed to
tune the nanoshell resonance spectra to reach high
absorption cross section in the NIR region. The thermal
and photochemical stability of the nanoparticles has been
tested and achieved by use of surfactants bearing
substituent groups for further functionalization.
Au-nanosphere and nanoshell of about 20 nm diameter
were conjugated to amminoacids and their interaction
was quantitatively followed by spectrophotometric and
AFM measurements.
These nanostructured materials having low toxicity and a
large surface easily processable can be used as selective
drug delivery systems and in photothermal treatments.
1. Menegazzo, F., Manzoli, M., Chiorino, A., Tabakova, T.,
Signoretto, M., Pinna, F., Perticone, N.; Journal of Catalysis,
2006, 237, 431 – 434.
1. J.L. West, N.J. Halas, Curr. Opin. Biotech. 2000, 11, 215-217.
2. P.K. Jain, K.S. Lee, I. El-Sayed, M. El-Sayed, J. Phys. Chem.
B, 2006, 110, 7238-7248 3. C.A. Mirkin et al., Science, 1997,
277, 1078. 4. J.L. West, N.J. Halas, Annu. Rev. Biomed. Eng.,
2003, 5, 285. 5. D. P.O’Neala, L.R. Hirschb, N.J. Halas, J.D.
Paynea, J.L. Westb, Cancer Lett., 2004 209, 171
41
O 4.7
Sostituzione cationica e proprietà in “bronzi di
tungsteno”
V. Massarottia, D. Capsonia, M.Binia, M.C. Mozzatib,
C.B. Azzonib, P. Galinettob
a
Dipartimento di Chimica Fisica “M. Rolla”
dell’Università e IENI-CNR, Viale Taramelli 16, 27100
Pavia. e-mail: [email protected]
b
CNISM-Dipartimento
di
Fisica
“A.
Volta”
dell’Università, Via Bassi 6, 27100 Pavia
Figura 2 – Immagini SEM (5.5kX) del campione puro (sinistra)
e drogato Fe (destra).
Informazioni sullo stato di valenza di ioni droganti e sulla
loro distribuzione sui siti cationici possono essere
ottenute dall’analisi dei segnali EPR attraverso un
confronto con i risultati ottenuti sui campioni
Ba6Ti2Nb8O30 (BTN) [3] di analoga struttura ma con Ti4+
e Nb5+ sui siti B e C (Figura 3).
Alcune famiglie di ossidi misti consentono sostituzioni di
cationi capaci di apportare significativi cambiamenti del
comportamento chimico fisico del composto. Le
variazioni di alcune proprietà fisiche possono così essere
sfruttate per applicazioni in diversi campi, dall’elettronica
alla catalisi, dall’elettro-ottica all’ottica non lineare. La
famiglia dei bronzi di tungsteno, di formula A6B2C8O30,
ha la struttura caratterizzata da tre differenti siti cationici
[1] (Figura 1), sui quali opportune sostituzioni con
elementi di transizione isovalenti o aliovalenti
consentono l’ampia modulazione di proprietà elettriche e
magnetiche richieste per applicazioni.
Derivative EPR Signals (arb. units)
BTN Mn 0.06
B
C
z
x
A
c
y
O2-
a
a
BZT Mn 0.06
BTN Fe 0.06
BZT Fe 0.06
b
BTN Fe 0.18
c
BTN Cr 0.06
BZT Cr 0.06 (x30)
1000
2000
3000
4000
5000
6000
B (gauss)
Figura 1 – Struttura di BZT con indicazione dei siti atomici.
Figura 3 – Confronto dei segnali EPR dei campioni drogati BZT
e BTN con differenti livelli di drogaggio.
Il reticolo ionico di Ba6Zr2Ta8O30 (BZT) [2], in cui Zr4+ e
Ta5+ occupano i siti ottaedrici B e C, è stato paragonato
ad un reticolo “vetroso”, capace di ospitare cationi di
transizione. Si può vedere che opportuni cationi M (Ni,
Co, Fe, Mn, Cr) possono distribuirsi sui siti Zr e Ta
assumendo diversi stati di valenza, determinabili con le
misure EPR. Il sito A viene occupato esclusivamente dal
grosso catione alcalino terroso, mentre la distribuzione di
Zr o Ta sui siti B e C viene indagata con il metodo di
Rietveld, cioè uno studio strutturale sulla base di misure
di diffrazione da polveri. Nel composto BZT il sito C
risulta occupato al 78% da ioni Ta5+ ed al 22% da ioni
Zr4+. Invece il sito B è occupato al 12.5% da Zr4+ ed
all’87.5% da ioni Ta5+.
Gli ioni droganti M sono selettivamente presenti sul sito
C rispetto all’altro sito B. L’indagine strutturale
suggerisce la maggiore deformazione dell’ottaedro C,
caratterizzato da sei diverse lunghezze di legame
comprese nell’intervallo 1.90-2.10 Å, rispetto all’ottaedro
B, che presenta 4 legami equatoriali uguali di 1.98 Å e
due legami apicali di 1.80 e 2.19 Å. Sulla base del valor
medio delle distanze di legame l’ottaedro C risulta più
dilatato dell’ottaedro B e la preferenziale sostituzione in
C può quindi essere ricondotta alla maggiore
deformazione del sito. Misure diffrattometriche e
microscopiche (Figura 2) evidenziano, in campioni
drogati con manganese e ferro, la formazione di cristalliti
di dimensione media tre volte maggiore rispetto a quelli
presenti nel campione puro o drogati con altri ioni (Ni,
Co, Cr).
I campioni drogati Mn e Fe mostrano segnali EPR tipici
di ioni Mn2+ e Fe3+ in matrici disordinate o vetrose.
Questo conferma che il sito ottaedrico C,
preferenzialmente occupato dai droganti, è caratterizzato
da una distribuzione di distorsioni.
Lo spettro micro-Raman del BZT ha alcune bande
caratteristiche comuni a quello del BTN ma, nonostante
le due strutture appartengano allo stesso gruppo spaziale
tetragonale (P4bm), i loro spettri Raman mostrano
differenze significative. Le larghe bande osservate nello
spettro BTN trovano corrispondenza con picchi Raman
stretti e ben definiti nelle stesse regioni spettrali. Il
campione BTN mostra uno scattering allargato attorno a
250 cm-1, praticamente assente in BZT dove si osserva un
picco stretto a 295 cm-1. Queste diverse caratteristiche
possono essere imputate a diverso grado di simmetria,
come si osserva in generale nel passaggio da struttura
tetragonale a ortorombica. In effetti passando da BTN a
BZT il comportamento degli spettri Raman è similare a
quello osservato nel titanato di bario con l’abbassamento
di temperatura, cioè con la transizione tetragonale →
ortorombico → romboedrico. Il restringimento dei picchi
Raman in BZT può essere giustificato dall’abbassamento
di simmetria locale dovuto ad occupanza di Zr e Ta negli
stessi siti precedentemente occupati da Ti e Nb in BTN.
D’altra parte una distribuzione di distorsioni già rilevata
da studi EPR e strutturali è più evidente in BZT che in
BTN.
42
Intensity (arb units)
0.4
[1] Ainslie KM, Bachelder EM, Borkar S, Zahr AS, Sen A,
Badding JV, Pishko MV, Cell Adhesion on Nanofibrous
Polytetrafluoroethylene (nPTFE), Langmuir 2007, 23, 747.
[2] Dinelli F, Murgia M, Levy P, Cavallini M, Biscarini F, de
Leeuw DM, Spatially correlated charge transport in organic thin
film transistors. Phys Rev Lett., 2004, 92, 116802.
[3] Bystrenova E, Facchini M, Cavallini M, Cacace M. G.,
Biscarini F, Multiple length scale patterning of DNA by stamp
assisted deposition, Angew. Chem. Int. Ed., 2006, 45, 4779.
BTN
BZT
0.3
0.2
0.1
200
400
600
-1
Raman Shift (cm )
800
1000
Figura 4 – Confronto fra spettri Raman di BZT e BTN puri.
1. Chi, E. O.; Gandini, A.; Ok, K. M.; Zhang, L.; Halasyamani,
P. S. Chem Mater, 2004, 16, 3616. 2. Massarotti, V.; Capsoni,
D.; Bini, M.; Azzoni, C. B.; Mozzati, M. C.; Galinetto, P. J.
Phys. Chem. C, 2007, 111, 6857-6861. 3. Massarotti, V.;
Capsoni, D.; Bini, M.; Azzoni, C. B.; Mozzati, M. C.; Galinetto,
P.; Chiodelli, G. J. Phys. Chem. B, 2006, 110, 17798.
O 4.8
Growth of neural cells on ultra thin organic
semiconductors
E. Bystrenovaa, I.Tonazzinia, P. Grecoa, S. Duttaa, P.
Stoliara, A. Lazara, C. Dionigia, M.G. Cacacea, C.
Martinib, M. Jelitaic, E. Madaraszc and F. Biscarinia
Fig.1: Optical micrograph, AFM in liquid and fluorescent
images obtain on astrocytoma and neuronal cells growth
on organic thin film.
a
CNR, ISMN-Istituto per lo Studio dei Materiali
Nanostrutturati,Via P. Gobetti 101, 40129 Bologna, I T A
L Y, [email protected]
b
Department of Psychiatry, Neurobiology, Pharmacology
and Biotechnology University of Pisa, Via Bonanno 6,
56126 Pisa, I TA L Y
c
Laboratory of Cell and Developmental Neurobiology,
Inst. of Experimental Medicine of Hungarian Academy of
Sciences, Szigony u. 43,1083 Budapest, H U N G A R Y
Many technological advances are currently
being developed for nano- and micro- fabrication,
offering the ability to create and control patterns of soft
materials with sub micrometric precision1.
In this work we report the deposition of cells on
organic semiconductor ultra-thin films. This is a first step
towards the development of active bio/non bio systems
for electrical transduction that could be integrated
directly in vitro. Thin films of pentacene molecules,
whose thickness was systematically varied between 1 and
50 nm, were grown by high vacuum sublimation2. Human
astrocytoma cells and NE-4C neural stem cells were
grown and maintained in culture in standard condition
o
(37 C, 95% humidity, 5%CO2) in medium supplemented.
Small molecules (PL, laminine, APTES, dodecylamine,
PEG etc.) were patterned onto the surface3 by templateassisted deposition in order to spatially modulate the cell
adhesion on the surface. Released pre-patterned
multilayers were exposed to cell culture medium
incubated at 37oC for 70h.
Viability of cells in time was measured as a
function of roughness and the characteristic morphology
of ultra thin organic film, as well as the features of the
patterned molecules. Optical fluorescence microscope
coupled to atomic force microscope was used to monitor
the presence, density and shape of deposited cells.
This work is supported by Project EU-NMP-STRP
032652 BIODOT.
43
SEZIONE
CHIMICA FISICA TEORICA E COMPUTAZIONALE
44
active site base with formation of an α-carbanion
intermediate, which donates two electrons to the flavin
and eliminates the α-hydroxyl proton in order to obtain
pyruvate.[3a,b] In the hydride transfer (HT) mechanism
(Scheme 1b), the active site base abstracts the lactate αhydroxyl proton and Hα is transferred to the flavin as a
hydride.[3c]
I5
Ab-initio molecular dynamics of solute-solvent
systems based on non periodic boundary
conditions: applications to spectroscopic
properties.
Nadia Regaa
a
Dipartimento di Chimica and INSTM, Universita'
'Federico II',Complesso Universitario di M.S.Angelo, via
Cintia, I-80126 Napoli, Italy, [email protected]
R
N
a)
N
NH
N
B:
We employ ab-initio dynamics to simulate systems in
aqueous solution.
The approach is based on the combination of QM/MM
molecular dynamics techniques using localized basis sets
and non-periodic boundary conditions, and a posteriori
high-level quantum mechanical calculations.
This integrated methodology allows for a detailed
analysis of the influence of stereoelectronic,
microsolvation and short-time dynamic effects on the
resulting spectroscopic parameters.
We present some pilot applications chosen as prototypes
to treat solvent effects of strategical importance in
biochemistry, with particular attention to the modulation
of spectroscopic properties.
Such a model represents a valid alternative to the
standard picture given by periodic boundary conditions
for modeling condensed phase systems.
R
N
O
O
COO -
R
COO -
R
NH
OH2
NH
OH2
R
N
N
R
N
O
N
NH
N
H
R
O
NH
N H+
O
COO -
R
O
NH
N
O
H
N
O
COO -
NH2
O
NH2 +
O
b)
R
N
R
N
N
O
N
NH
NH
N
N
H
H
O
COO -
R
OH2
NH
O
R
O
COO -
NH
O 2+
:B
Scheme 1: L-lactate oxidation to pyruvate in Fcb2 via: a) PA
mechanism; b) HT mechanism.
1. Rega N.; Brancato G.; Barone V.; Chem. Phys. Lett. 2006,
422, 367.
2. Brancato G.; Barone V.; Rega N.; Theor. Chem. Acc., 2007,
DOI:10.1007/s00214-006-0216-z .
In order to help solving the Fcb2 mechanistic issue, we
have addressed the question of the reactivity of lactate
and of its deprotonated forms, i.e. the α-carbanion and the
alkoxide, via ab initio calculations.[4] The geometries of
the isolated species were optimized at the MP2/cc-pVTZ
level, harmonic frequencies and atomic charges were
calculated and the electronic structure investigated by
NBO analysis. [5] In L-lactate, the Cα-Hα bond is longer
and its stretching frequency lower with respect to the
methyl C-H bonds. In the lactate alkoxide, which is more
stable than the carbanion by 22.7 kcal mol-1, the Cα-Hα
bond is significantly longer than in L-lactate (0.039 Å)
and is characterized by a large red shift of its stretching
frequency (462 cm-1); moreover an increase of electronic
charge on Hα of ~ 0.2 e is found. NBO deletion analysis
[5] indicated that such a significant Cα-Hα bond
weakening is due to negative hyperconjugation, which
implies electron density transfer from the lone pairs on
the hydroxyl oxygen to the C-H σ* antibonding
orbital.[6] The antibonding character of the Cα-Hα bond
of lactate is greatly enhanced in the alkoxide, which is
therefore poised for pyruvate conversion, while α-proton
abstraction does not contribute to weaken the carbanion
α-OH bond in order to obtain the reaction product. These
results indicated the HT path as the oxidation mechanism
favoured by the substrate.
The effect of the enzyme active site residues on the
intrinsic reactivity was investigated on a model of the
Fcb2- L-lactate Michaelis complex [7] using first
principles molecular dynamics.[8] Simulation results
indicated that the binding of the substrate with the active
site residues enhances the n-σ* interaction responsible of
the Cα-Hα bond weakening, already present in the
isolated lactate. Therefore, the finite temperature
behaviour in the model enzyme site also supports the HT
mechanism and suggests that this enzyme may accelerate
dehydrogenation by amplifying the lactate intrinsic
O 5.1
On the active role of substrate reactivity in the
context of enzymatic dehydrogenations: a
theoretical investigation.
Gloria Tabacchia, Maria A. Vanonib, Aldo Gambaa,
Ettore Foisa
a
Dipartimento di Scienze Chimiche ed Ambientali and
INSTM Università degli Studi dell’Insubria, Via Lucini
3, I-22100 Como (Italy), [email protected]
b
Dipartimento di Scienze Biomolecolari e Biotecnologie
Università degli Studi di Milano, Via Celoria 26, I-20133
Milano (Italy)
Aim of the present study is trying to establish, by first
principles calculations of physico-chemical properties of
enzymatic dehydrogenation substrates, how the reactivity
of
specific substrates is related to the reaction
mechanism adopted by the corresponding enzymes.
Flavoenzymes, a class of oxidoreductases implicated in a
variety of fundamental redox reactions of cell
metabolism[1], have been chosen as test cases because
they may accomplish substrate oxidation through
different reaction paths.[2] For instance, in spite of the
wealth
of
available
experimental
data,
the
dehydrogenation mechanism of α-hydroxyacids to the
corresponding ketoacids is still debated.[2-3] The
prototype enzyme flavocytochrome b2 (Fcb2) catalyzes
the oxidation of L-lactate to pyruvate.[3] According to
the proton abstraction (PA) or carbanion mechanism
(Scheme 1a), the lactate α-proton Hα is abstracted by an
45
reactivity via hydrogen bonding interactions with the
active site base.
In order to investigate whether a more general
relationship may be established between the substrate
intrinsic reactivity and the dehydrogenation mechanism
operative in flavoenzymes, geometry optimizations,
frequency calculations and NBO analysis were also
performed on a series of substrates of other flavin
containing enzymes for which the mechanism is well
established.[1-3,7,9]
For each isolated substrate,
calculated bond elongations, frequency red shifts, and
energetic contribution of n-σ* interaction are in line with
the oxidation mechanisms occurring in the corresponding
enzyme active sites, thus providing further support to the
relevance of negative hyperconjugation in enzymatic
dehydrogenations. On a general ground, from the present
study it emerges that intrinsic substrate properties may
drive the catalytic path in enzymes active sites.
a) dipolar coupling constants should be considered for
the proper analysis of the hyperfine structure in rotational
spectra and
b) that dipolar-coupling tensors provide an alternative
way for determining bond distances (based either on the
analysis of rotational or NMR spectra).
In principle, the determination of the dipolar coupling
constants just require knowledge of the molecular
equilibrium geometry, though quantum-chemical
investigations are necessary to evaluate the vibrational
corrections. In this presentation we will compare
computed dipolar coupling constants for several small to
medium-sized molecules to experiment, and demonstrate
the importance of including vibrational corrections for
accurate predictions. In addition, we will show how
experimental dipolar coupling constants together with
computed vibrational corrections can be used to derive
equilibrium bond distances.
1. De Colibus, L.; Mattevi, A. Curr. Opin. Struct. Biol. 2006, 16,
722-728.
2. Fraaije, M.W.; Mattevi, A. Trends Biochem. Sci. 2000, 25,
126-132.
3. Lederer, F. in: Chemistry and Biochemistry of Flavoenzymes
1991 (Müller, F., Ed.) pp.153-242, CRC Press, Boca Raton, FL.;
b) Lederer,F.; Amar, D.; Ould Boubacar, A.K.; Vignaud, C. in
Flavins and Flavoproteins, ed. T. Nishino, R. Miura, M.
Tanokura and K. Fukui, ArchiTect Inc.,Tokyo, 2005, pp. 193204; c) Fitzpatrick, P.F. Bioorganic Chemistry 2004, 32, 125139.
4. Gaussian 98, Revision A.11.3, Frisch, M. J. et al., Gaussian,
Inc., Pittsburgh PA, 2002.
5. a) Reed, A.E.; Curtiss, L.A.; Weinhold, F. Chem. Rev. 1988,
88, 899-926; b) Glendening, E.D.;Reed, A.E.; Carpenter, J.E.;
Weinhold, F. NBO 3.1; c) Goodman, L.; Sauers, R.R. J. Comp.
Chem.A 2007, 28, 269-275.
6. a) DeFrees, D.J.; Bartmess, J.E.; Kim, J.K.; McIver, T.T.;
Hehre, W.J. J. Am. Chem. Soc. 1977, 99, 6451-6452; b)
DeFrees, D.J.; Hassner, D.Z.; Hehre, W.J.; Peter, E.A.;
Wolfsberg, M. J. Am. Chem. Soc., 1978, 100, 641-643; c) Lii,
J.H.;.Chen, K.H.; Allinger, N.L. J. Phys. Chem. A 2004, 108,
3006-3015.
7. a) Vanoni, M.A.; Tabacchi, G.; Lederer, F.; Gamba, A.; Fois,
E., in Flavins and Flavoproteins, ed. T. Nishino, R. Miura, M.
Tanokura and K. Fukui, ArchiTect Inc.,Tokyo, 2005, pp. 281287; c) Tabacchi G., Vanoni, M.A.; Gamba, A.; Fois, E.
ChemPhysChem 2007 in press.
8. a) Car, R.; Parrinello, M. Phys. Rev. Lett. 1985, 55, 24712474; b) CPMD V3.11 (www.cpmd.org) Copyright IBM Corp.
1990-2006, Copyright MPI für Festkörperforschung Stuttgart
1997-2001.
9) Tilocca,
A.;
Gamba, A.; Vanoni, M.A.; Fois, E.;
Biochemistry 2002, 41, 14111-14121
O 5.3
Reazione di idrolisi della molecola di diborano in
soluzione tramite simulazioni di dinamica
molecolare ab initio
Elisa Di Pietroa, Gianni Cardinia,b, Vincenzo Schettinoa,b
Dipartimento di Chimica, Univerista' di Firenze, via
della Lastruccia 3, 50019 Sesto Fiorentino, Firenze,
[email protected]
b
European Laboratory for Nonlinear Spectroscopy
(LENS), via Nello Carrara 1, 50019 Sesto Fiorentino,
Firenze
a
Tramite calcoli di dinamica molecolare ab initio di tipo
Car-Parrinello1 e' stata studiata la reazione di idrolisi del
diborano in soluzione acquosa2. La reazione totale e' stata
divisa in due parti, entrambe simulate nell'insieme Blue
Moon3 per ottenere informazioni sia sul meccanismo di
reazione che sul profilo energetico.
La prima parte della reazione prevede la rottura della
molecola di diborano in una molecola di H2BOH, in un
protone e in uno ione BH4-, che, successivamente diventa
il reagente della seconda parte della reazione. L'energia
libera di Helmoltz relativa al primo step reattivo e' di
13.00 kcal/mol.
Nella seconda parte della reazione lo ione BH4- reagisce
con due molecole d'acqua dando luogo ad un'altra
molecola di H2BOH, uno ione ossidrile e due molecole di
idrogeno.
Nel complesso emerge chiaramente che l'effetto del
solvente sulla reazione e' piccolo, in particolare dallo
studio della struttura elettronica di reagenti e prodotti e'
possibile individuare solo lievi spostamenti dei doppietti
elettronici relativi alla posizione dei centri di Wannier.
Infine, e' stata individuata l'esistenza di un addotto,
O 5.2
Vibrational Corrections to Dipolar Coupling
Constants: an Alternative for Determining
Equilibrium
Distances
from
Rotational
Spectroscopy
BH3·H2 , il quale e' legato da un debole legame covalente
a due elettroni e tre centri, che avviene tra gli elettroni
nell'orbitale di legame della molecola di idrogeno e
l'orbitale vuoto dell'atomo di boro nella molecola di BH3.
A 300 K il complesso e' rimasto stabile in soluzione per
tutta la durata della simulazione (10 ps).
Cristina Puzzarinia, Thorsten Metzrothb, Jürgen Gauss
a
Dipartimento di Chimica ``G. Ciamician'', Università
degli Studi di Bologna, Via Selmi 2, I-40126 Bologna,
Italy, [email protected]
b
Institut für Physikalische Chemie, Universität Mainz,D55099 Mainz, Germany
1. Car, R.; Parrinello, M.; Phys. Rev. Lett., 1985, 55, 2471 –
2474. 2. Di Pietro, E.; Cardini, G.; Schettino, V.; Phys. Chem.
Chem. Phys., 2007, accepted. 3. Carter, E; Ciccotti, G.; Hynes,
J.; Sprik, M..; Chem. Phys. Lett., 1989, 156, 472.
The main interaction between the spins of two nuclei is the
dipole-dipole coupling between their magnetic moments. The
importance of these interactions lies in the facts that
46
agreement with those obtained with expensive post-HF
methods. Moreover, thanks to purposely tailored GTO
basis set, that minimizes the BSSE and provides
affordable computational costs, we performed firstprinciple molecular dynamics of the benzene dimer
within the ADMP scheme3: average structures and
computed frequencies will be dicussed.
O 5.4
From paratropic ring currents to closed-shell
molecular magnets
Guglielmo Monaco, Riccardo Zanasi
Dipartimento di Chimica,Università di Salerno, via ponte
Don Melillo, 84084 (SA) Fisciano, [email protected]
a) Permanent address: Dipartimento di Chimica, Università di
Napoli Federico II, Via Cintia I, 80126 Napoli, Italy
1. Muller-Dethlefs, K.; Hobza, P.; Chem. Rev., 2000, 100, 143 –
167. 2. Grimme, S.; J. Comput. Chem., 2006, 27, 1786 –1799.
3. Schlegel, H. B.; Iyengar, S. S.; Li, X.; Millam, J. M.; Voth, G.
A.; Scuseria, G. E.; Frisch, M. J. J. Chem. Phys., 2002, 117,
8694
According to the laws of classical electromagnetism, the
free electrons in a metallic ring are set in circulation by
an external magnetic field and generate a magnetic field
which is opposed to the external field. This phenomenon
is common to the vast majority of closed-shell molecules.
However quantum mechanics also allows the electrons to
set in a paratropic circulation, which generates a field
which adds to the external field, as happens in open-shell
systems. Paratropic currents are generally too weak to
dominate the magnetic behaviour of the molecule.
Antiaromatic annulenes are a very interesting exception
although they are generally unstable in the planar form
with the most promising paratropic current. In the effort
to design molecular systems which could exploit the
characteristics of these systems, we demonstrated a novel
theorem on the factorization of Kekulé counting, which
guided us to design novel molecular systems ([8,5]coronene and [12,5]-coronene), for which ab initio
calculations gave a paramagnetic response along a
molecular axis, which in [12,5]-coronene was so strong to
dominate the isotropic magnetic behaviour of the
molecule.1 These coronenes are unique in that the two
concentric rings of the molecular system both show a
paratropic ring current, which is not a simple
consequence of the fact that both rings have 4n pi
electrons, but stems form the peculiar connectivity of the
systems. The utility and the limitations of the
factorization of Kekulé count as a useful tool for
molecular design and for the interpretation of density
currents have been investigated in several cases.
O 5.6
Dynamics of the photodeactivation processes in
DNA nucleobases
Fabrizio Santoroa, Roberto Improtab
a
Istituto per i Processi Chimico Fisici del CNR, Via
Moruzzi 1,I-56124 Pisa,[email protected]
b
Roberto Improta, Istituto di Biostrutture e Bioimmagini
del CNR, via Mezzocannone 8, I-80131 Napoli.
Sunlight is essential to life but, as the other side of the
coin, it is also a potential carcenogenic agent, and
consequently evolution has selected highly photostable
molecules to encode the genomic information. Their
photostability is ensured by highly efficient decay
pathways that transform the electronic excitation into
vibrational energy and finally into heat [1].
The study of DNA and RNA photostability has
been discouraged for a long time by the same reason that
makes it so interesting: the extreme speed of the
deactivation processes that is responsible for the very low
quantum yields of fluorescence of the purine and
pirimidine bases, traditionally considered as non
fluorescent at all. Recently, the impressive progresses in
time-resolved spectroscopies, up to the femtosecond
regime, and the simultaneous advances in theoretical and
computational methods, have allowed a true renaissance
of the field. The deactivation mechanism of the single
nucleobases after the UV π π* excitation has been
recently extensively investigated
by different
experiments, from transient absorption to fluorescence
up-conversion, in several solvents. It is now clear that the
deactivation is ultrafast (from 200 fs in uracyl to some ps
for the slower component in adenine) and can show
mono- or bi-exponential features [1]. A reliable picture is
now emerging for these processes, also thanks to the
important help of theoretical and computational studies.
They have allowed to locate the conical intersections (CI)
[2-3], the funnels that drives back the system to the
ground electronic state, to describe the minimum energy
path (MEP) from the Franck-Condon (FC) to the CI
regions, and to explore some portions of the excited
potential energy surfaces (PES) [4-5]. Nonetheless, the
description of the process remains static, and many issues
are still to be clarified, concerning e.g. the solvent effect
and the possible role of intermediate n π* states.
While the “static” computational study of the
relevant PES and their topology is an important first step,
there is no doubt that a full understanding of the
mechanism may only come from a careful investigation
1. Monaco, G.; Zanasi, R.; Fowler, P. W.; Lillington, M.;
Angew. Chem. Int. Ed., 2007, 46, 1189-1192.
O 5.5
DFT-D study of the benzene dimer: structural
minima, energies and molecular dynamics.
Michele Pavonea
Department of Chemistry Princeton University, 08540
Princeton NJ, USA; [email protected]
The benzene dimer is the simplest model for weak noncovalent interactions of the aromatic π−π type. Despite
the small energy amount involved in the benzenebenzene binding (1-3 kcal/mol), the aromatic π−π
interactions have been proven to play a crucial role as
stabilizing forces in biological macromolecules,
supramolecular self-assembly and molecular recognition.
For these reasons, in the past decades there has been a
great theoretical and experimental progress in a joint
effort to characterize the structures and energetics of
benzene clusters.1
Here we report the structures, the binding energies and
the harmonic frequencies of the benzene dimer minima,
computed at the well-known B3LYP density functional
theory level, with the inclusion of a semiempirical
correction term to properly account van der Waals forces,
as recently proposed by Grimme.2 Our results are in fair
47
b
of the nuclear dynamics (including solvent modes). In
fact, in presence of a large kinetic energy an excited wave
packet may explore regions far from the MEP, while a
given barrier along its way is more or less effective
depending on the carried momentum distribution.
In this contribution we report our results, based
on an extensive TD-DFT investigation of the excited
energy surfaces of uracil and 5-fluorouracil in acetonitrile
and aqueous solution, allowing the investigation of both
the substituent and the solvent effect. We employ the
PBE0 hybrid functional, while the solvent is described
both at implicit level, by the polarizable continuum
method, and by explicitly including the water molecules
relevant for hydrogen bonds. We show strong static [5]
and dynamical arguments in favour of a relevant role
played by an intermediate n π* state in the decay of the
initially excited π π* population, thus confirming the
very recent experimental findings [6]. Our results further
suggest that the solvent can drastically tune the n π*
role in the deactivation process.
The understanding of the dynamics of isolated
nucleobases is the necessary pre-requisite for a full
comprehension of the deactivation processes in the real
bio-polymers, where nonetheless inter-bases interactions
might modify the efficiency of the single-base decays and
open new competitive pathways [7-9]. As stated by
Kohler, an expert in the field, in 2004 “the greatest future
challenges concern excites dynamics in base multimers,
including natural DNAs and RNAs” [1].
We present our TD-DFT results on adenine
dimers and trimers pointing out a strong tendency to
localize the Uv excitation on a single monomer but also,
at the same time, the existence of minima on the firstexited state corresponding to dimer charge-transfers,
confirming the existence of competitive decay pathways
[10].
Dipartimento di Chimica Strutturale e
Stereochimica Inorganica, via Venezian 21, Milano
c
Dipartimento di Chimica,Università di Siena, via
A. Moro, Siena.
In the last years remarkable chemical and physical efforts have
been addressed toward the realization and the study of composite
compounds which can be employed in the technological field. In
several cases the complexity of the observed phenomena makes
very difficult an accurate knowledge of the underlying
mechanisms through an experimental approach alone. On the
other side, nowadays the ability of the density functional theory
to reproduce the chemical and physical properties of large
complexes is satisfactory. In this communication we report the
synthesis and the spectroelectrochemical and computational
characterization [1,2] of compounds 1-4 (Fig.1) containing one
or two platinum clusters linked to an ethynylferrocene or to an
ethynylbiferrocene , in which a MMCT is observed upon
oxidation.
O
C
Pt
P
P
Pt
Pt
P
Fe
C
O
1
O
C
O
P Pt C
P
Pt
Pt
Pt
Pt Pt P
P
C
O CO
Fe
Fe
2
O
C
Pt P
P
1. Crespo-Hernández, C. E. et al. ; Chem. Rev., 2004, 104, 1977.
2. Serrano-Andrés, L. et al.; Proc Natl. Acad. of Science, USA
2006, 103, 8691
3. Matsika, S; J. Phys. Chem. A, 2005, 105, 7538.
4. Markovitsi, D. et al. ; J. Am. Chem. Soc., 2005, 127, 17130.
5. Santoro, F.; Barone V.; Gustavsson, T.; Improta, R.; J. Am.
Chem. Soc. 2006, 128, 16312
6. Hare, P. M. et al.; Proc. Natl. Acad. Science, USA, 2007, 104,
435
7. Crespo-Hernández C. E. et al ; Nature, 2005, 436, 1141;
ibidem 2006, 441, E8.
8. Markovitsi, D.et al.; Nature, 2006, 441, E7, (2006).
9. Kwok ,W.-M. et al. ; J. Am. Chem. Soc., 2006, 128, 11894.
10. Santoro, F.; Barone V.; Improta, R Proc Natl. Acad. of
Science, USA; 2007, in press
Pt
Pt
P
C
O
O
C
P Pt
Pt
P
Pt
P
C
O
Fe
O
C
O
C
Pt P
P
Pt
Pt
P
Pt
C
O
P
3
Fe
Fe
P
Pt
P
Pt
C
O
4
Figure 1
The aforesaid compounds have been studied using
density functional methods with B3LYP functional and
LANL2DZ as basis set with polarization d functions on P
atoms
O 5.7
A combined approach of theory and experiment
for the study of platinum clusters derivatives
a
1. a) Tarraga, A.; Molina, P.; Curiel, D.; Velasco, M. D.;
Organometallics, 2001, 20, 2145, b) Jiao, J.; Long, G. J.;
b
Gabriele Manca , Alberto Albinati , Samantha
Bruzzonea, Fabrizia Fabrizi de Bianic, Carla
Guidottia, Piero Leonia, Lorella Marchettia, Piero
Zanelloc
Grandjean, F.; Beatty, A.M.; Fehlner, T. P.; J. Am. Chem. Soc.,
2003, 125, 7522, 2. Long, N. J.; Martin, A. J.; Vilar, R.; White,
A. J. P.; William, D. J.; Younus, M.; Organometallics, 1999,
18, 4261.
a
Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, via Risorgimento 35, Pisa.
Email:[email protected]
48
O 5.8
Insight into Elastic properties of binary alkali
silicate glasses: prediction and interpretation
through atomistic simulation techniques.
Alfonso Pedone,a Gianluca Malavasi,a Alastair N.
Cormack,b Ulderico Segrea and M. Cristina Menziani.a
a
Dipartimento di Chimica, Università di Modena e
Reggio Emilia, via G. Campi 183, 41100 Modena.
[email protected]
b
Kazuo Inamori School of Engineering, New York State
College of Ceramics, Alfred University, Alfred, NY
14802, USA
Molecular
dynamics
simulations
and
energy
minimization techniques have been applied for the first
time to determine the whole set of elastic properties
(Young’s modulus, shear modulus, bulk modulus and
Poisson’s ratio) of alkali silicate glasses with different ion
modifiers (Li, Na and K) in the range 0 to 30% mol of
alkaline oxide. The force-field recently developed by
Pedone et al.1 has been implemented in the DLPOLY
package2 which was used to create glass structures via a
melt-quench process.3 The static method included in the
GULP package4 was used to calculate the elastic
properties. Excellent agreement has been found between
the simulation results and the experimental data. The
peculiar behaviour of the Li containing glasses with
respect to the Na and K ones is discussed in terms of the
glass structural features. It was found that the elastic
properties variations as a function of alkali addition can
be explained by three concurrent factors:5 1) the
depolymerization of the silica network; 2) the
establishment of alkali-Non-Bridging-Oxygen bonds
which increase the cohesion of the glass; and 3) the
increase of the glass packing density due to decreasing of
the free volume.
1. Pedone, A.; Malavasi, G.; Menziani, M. C.; Cormack, A. N.;
Segre, U., J. Phys. Chem. B 2006, 110, 11780.
2. Smith, W.; Forester, T. R., J. Mol. Graph. 1996, 14, 136.
3. Malavasi, G.; Menziani, M. C.; Pedone, A.; Segre, U., J. NonCryst. Solids 2006, 352, 285.
4. Gale, J. D.; Rohl, A. L., Mol. Simul. 2003, 29, 291.
5. Pedone, A.; Malavasi, G.; Cormack, A. N.; Segre, U.;
Menziani, M. C., Chemistry of Materials 2007, in Press.
49
CONTRIBUTI
POSTER
50
SEZIONE
CHIMICA FISICA BIOLOGICA ED AMBIENTALE
51
cavity and for some external aminoacids, were studied in
order to characterize the binding process. 1H NMR
studies on solutions of low-spin Cyano-MetMyoglobins
(CNMb) from pig and horse pressurized with xenon gas
show that, at a first approximation, the Xe1 cavity is the
main binding site for xenon in horse Mb. A two-site
thermodynamic model allows determining the binding
constant, giving results in very good agreement with
literature.
Moreover, by exploiting hyperfine interactions between
the heme iron and the protons of residues surrounding the
active site of horse CNMb, we collected evidences of
local distortions caused by the guest xenon on the
structure of the protein.
1
H and 129Xe NMR measurements are in good agreement
and it can be demonstrated that while the Xe1 cavity
represents the principal binding site of xenon in horse
Mb, a second cavity must be considered in pig Mb. The
model adopted allows distinguishing between xenonprotein specific and non-specific interactions. The results
undoubtedly show that binding of xenon to internal sites
of the proteins is strongly influenced by the size and
geometry of the cavity. The results are confirmed and
substantiated by studying the myoglobins of sheep and
rabbit.
P 1.1
Nuclear Magnetic Resonance of
structural characterization of
cavities of Myoglobins
129
Xe and 1H:
hydrophobic
Roberto Anedda1, Benedetta Era2, Antonella Fais2,
Matteo Ceccarelli3, Marcella Corda2, Mariano Casu1 and
Paolo Ruggerone3,4
1
Dipartimento di Scienze Chimiche, Università di
Cagliari, 09042 Monserrato (CA), Italy.2Dipartimento di
Scienze Applicate ai Biosistemi, Università di
Cagliari,09042 Monserrato (CA), Italy.3CNR-INFM
SLACS, Dipartimento di Fisica, Università di
Cagliari,09042 Monserrato (CA), Italy.4CNR-INFM CRS
DEMOCRITOS, SISSA, via Beirut 2-4, 34014 Trieste,
Italya
The relevance of an experimental technique relies on the
possible manifold information that can be extracted but
also on its complementing attitude. An example is the use
of 129Xe NMR as a powerful and attractive biomolecular
probe for structural characterization of proteins. The
chemical inertness of xenon, the polarizability of its
electronic cloud, i.e. the sensitivity of its NMR
parameters (chemical shift, line shapes, relaxation rates)
toward non-bonded local environment and its
hydrophobic character make this noble gas an ideal probe
for the characterization of hydrophobic cavities within
proteins1.
Testing the ability of xenon as an efficient
biomolecular probe of cavities in globular proteins and,
particularly, in myoglobins (Mbs) is crucial to extract
important information on their structure and function, but
at the same time challenging due to the presence of
different interaction sites besides the heme iron.
However, the possibility to easily tune the oxidation state
of the metal ion gives the unique opportunity to study
interactions of different physical nature in the same
protein, which are sensed by both the guest and the host
itself.
Despite a number of progresses have recently
significantly improved the technique, many issues
concerning the molecular details of the binding process
and on possible local distortions induced by xenon in the
host structure are still unclear. Moreover, the scientific
interest toward this technique is amplified by the possible
use of xenon in clinical imaging and anesthesia.
Clearly, hints on the characterization of cavities and
xenon-protein affinity can be achieved by comparatively
studying myoglobins of different species or mutated
myoglobins, as in a recent NMR investigation of the pig
There, the
and horse metmyoglobins (MMbs)2.
combined use of the 129Xe chemical shift and the 129Xe
spin lattice relaxation rate as a function of xenon and
protein concentration has unraveled the influence of the
structure and/or hydrophobicity of a cavity on its xenon
occupancy. Horse and pig MMbs differ by 14 amino
acids, mostly located on the protein surface. Only one
difference involves the proximal cavity with the
isoleucine 142 (Ile142) in horse Mb replaced by a
methionine (Met142) in pig. The residues lining the
proximal cavity (also called Xe1) in horse and pig Mbs
are highlighted in the Figure. The study clearly supported
the presence of xenon on the Xe1 site in pig MMb, which
is, however, less populated than in the horse MMb,
pointing out the existence of other binding sites besides
Xe1.
Myoglobins from different species (horse, pig, sheep,
rabbit) which differ for aminoacid composition of Xe1
(a)
(b)
Figure: Residues lining the Xe1 cavity in (a) horse
(Leu89, Ala90, His93, Leu104, Phe138, Ile142, Heme)
and (b) pig (Leu89, Ala90, His93, Leu104, Phe138,
Met142, Heme) Mbs. The figures are obtained with the
visualization program VMD (Humprey et al. 1996).
1. Goodson, B.M.; J. Magn. Reson. 2001, 155, 157 – 216. 2.
Corda, M.; Era, B.; Fais, A. and Casu, M.; Biochim. Biophys.
Acta 2004, 1674, 182 – 192.
P 1.2
Application of ISORROPIA and SOAP modules
within CAMx model for PM simulation
Elena Chianese,b Guido Barone,a Angelo Ricciob
a
Dipartimento di Chimica, Università di Napoli
“Federico II”, via Cintia, Napoli.
b
Dipartimento di Scienze Applicate, Università degli
Studi di Napoli “Parthenope”, via De Gasperi 5, Napoli
CAMx1 air quality model allows the study of emission,
reaction and dispersion of gaseous pollutants emitted by
anthropogenic and biogenic sources. Air quality problems
are complicated by the presence of heterogeneous phases,
particularly particulate matter. Atmospheric PM can be
produced by gaseous precursors reactions, both from
inorganic and organic species.
In this work we use ISORROPIA2 and SOAP3 modules
for the study of inorganic and organic secondary aerosols
from their precursors, for European and Italian domains;
52
particularly we present the comparison
simulated and observed data for 2001 year.
between
1. O. Carp; C. L. Huisman; A. Reller; Progress in Solid State
Chemistry, 2004, 32, 33-177.
1
Comprehensive Air quality Model with eXtension (see
http://www.camx.com).
2
Nenes, A.; Pilinis, C.; Pandis, S.N; Aquatic Geochemistry,
1998, 4, 123-152.
3
Strader, R.; Lurmann, F.; Pandis, S.N.; Atmos. Environ., 1999,
33, 4849-4863.
P 1.5
Il metano ed il futuro del clima.
Elena Chianeseb, Giuseppina Pirontia, Guido Baronea,
Angelo Ricciob.
a
Dipartimento di Chimica, Università di Napoli
“Federico II”, via Cintia, Napoli.
b
Dipartimento di Scienze Applicate, Università degli
Studi di Napoli “Parthenope”, via De Gasperi 5, Napoli
P 1.3
An application of OSAT probing tool in
Southern Italy
Molti studi autorevoli sono concordi nell’attribuire alle
attività umane l’incremento dell’effetto serra e le
variazioni climatiche che ne conseguono [1] [2].
Le sostanze alle quali sono ascritti tali effetti sono
sostanzialmente la CO2 (il cui aumento in atmosfera è
stato dimostrato mediante carotaggio ed analisi dei
ghiacciai), gli ossidi di azoto (in particolare nella forma
di N2O), i CFC e gli HFC e FC (che hanno sostituito i
primi in molte applicazioni; questi, e in particolare gli
FC, hanno tempi di permanenza media molto lunghi in
atmosfera). In realtà esiste un altro pericolo per
l’aggravarsi dell’effetto serra da associare al gas CH4, la
cui concentrazione sta aumentando in associazione
all’espansione delle risaie e degli allevamenti (in
particolare di bovini) ai quali vanno aggiunti i processi
fermentativi naturali che si hanno nelle paludi e nei
termitai.
Oltre a queste fonti di metano “accertate” altre fonti
possano contribuire (in particolare proprio a seguito di un
incremento della temperatura, dunque come feedback
positivo dell’effetto serra stesso) all’incremento delle
emissioni di metano; in particolare può liberarsi il metano
attualmente contenuto nei cristalli di gas idrati presenti in
enormi depositi nel permafrost circumartico e nelle
scarpate continentali [3].
In questo lavoro verranno dunque illustrate le
caratteristiche salienti di queste strutture e verranno
avanzate ipotesi sui possibili effetti che un loro
scioglimento giocherebbe sul clima.
Elena Chianeseb, Alessia Riccioa, Guido Baronea, Angelo
Ricciob.
a
Dipartimento di Chimica, Università di Napoli
“Federico II”, via Cintia, Napoli.
b
Dipartimento di Scienze Applicate, Università degli
Studi di Napoli “Parthenope”, via De Gasperi 5, Napoli
Air quality problems are related to many substances in
the atmosphere directly generated by human activities or
produced by reactions involving gaseous precursors.
Among them ozone, produced by VOC and NOx
photochemical reactions, plays a key role in determining
human health damages and monuments degradation.
Strategies for reduction of secondary atmospheric
pollutants, as ozone, require the knowledge of many
factors as: precursor emission, spatial location of sources,
and so on.
All these parameters cannot be forecast by an air quality
model; in this work we present the study of ozone
formation in a summer period using CAMx model1 with
OSAT2 probing tool, discussing results on ozone
formation limiting conditions, sources and areas
producing precursors.
P 1.4
PM INDOOR POLLUTION REDUCTION BY
TiO2 FILMS.
1. IPCC. Climate Change. The scientific basis.
www.grida.no/climate/ipcc_tar/wg1/index.htm, 2001.
2. Crutzen P. J.; Benvenuti nell’antropocene. Mondadori, 2005.
3. Carroll J.; Natural gas hydrates, a guide for Engineers. Gulf
Professional Publishing, Elsevier, 2003.
Human exposure to urban atmospheric pollutants can
determine health problems; different substances are
responsible of these effects, particularly organic
pollutants, nitrogen and sulphur oxides, ozone and fine
particulate matter.
In the last years, it was established that these substances
can determine harmful effects also in indoor ambient,
specially in not well aerated conditions or in presence of
source emission.
For that reason researches are devoted to the
experimentation of materials1 that can determine
pollution reduction both for outdoor and indoor ambient.
In this work we present a testing made with TiO2 paints
for the reduction of PM2.5 produced form smoke
activity.
P 1.6
Elena Chianeseb, Giuseppina Pirontia, Guido Baronea,
Angelo Ricciob.
a
Dipartimento di Chimica, Università di Napoli
“Federico II”, via Cintia, Napoli.
b
Dipartimento di Scienze Applicate, Università degli
Studi di Napoli “Parthenope”, via De Gasperi 5, Napoli
Conformational stability of a thermostable
phosphotriesterase from the archaeon Sulfolobus
solfataricus (SsoPox)
P. Del Vecchioa, P. Carulloa, G. Baronea, L. Meroneb, M.
Rossib, G. Mancob
a
Department of Chemistry, University “Federico II”of
Naples,
via Cintia, 80126 Naples, Italy, [email protected]
b
Institute of Protein Biochemistry, via P. Castellino,
80131 Naples, Italy
Organophosphate (OPs) degrading enzymes have become
the focus of recent attention because of their potential
53
utility for the detoxification of chemical wastes, chemical
warfare
agents,
and
agricultural
pesticides.
Organophosphate compounds such as parathion
constitute the largest class of insecticides currently used
in the industrialized countries1. The lack of persistence of
these pesticides in the soil has been attributed to their
susceptibility to microbial transformation. Enzymes that
catalyse the hydrolysis of the phosphoester bonds in OPs
are known from several different bacterial species and are
termed phosphotriesterases (PTEs). Among them, the
homodimeric enzyme from Pseudomonas diminuta has
received considerable attention on its use as a
bioremediation agent and both functional and structural
studies have been reported2,3. Recently, some of us,
cloned a new gene from the hyperthermophilic archaeon
Sulfolobus solfataricus MT4, coding for a putative
protein reported to show sequence identity with the
phosphotriesterase-related protein family (PHP), named
SsoPox. This was the first phosphotriesterase to be
reported from a hyperthermophilic archaeon4.
Here we report a thermodynamic characterization of
SsoPox performed by means of thermal and denaturantinduced unfolding, using circular dichroism (CD) and
fluorescence measurements. SsoPox enzyme shows a
very high denaturation temperature and a three-state
mechanism on the GuHCl-induced unfolding. The results
are compared with the literature data on the mesophilic
enzyme from Pseudomonas diminuta5.
delle caratteristiche fenomenologiche. Si illustreranno le
problematiche di queste simulazioni, con alcuni esempi di
marmi provenienti da cave antiche del Mediterraneo.
1. Donato Attanasio, Ancient white marbles-Analysis and
identification by paramagnetic resonance spettroscopy,
L’erma di Bretschneider, Roma 2003
2+
Spettro di Mn in marmo bianco
3000
3200
3400
3600
B/Gauss
1. Mulbry, W. W.; Karns, J. S. ; Appl. Environ. Microbiol, 1988,
54, 2566-2571. 2. Benning, M. M.; Shim, H.; Raushel, F.;
Holden, H. M.; Biochemistry, 2001, 40, 2712-2722. 3. Dumas,
D.P. ; Caldwell, S. R.; Wild, J. R.; Raushel, F. M.; J. Mol. Biol.,
1989, 264, 19659-19665. 4. Merone, L.; Mandrich, L.; Rossi,
M.; Manco, G. ; Extremophiles, 2005, 9, 297-305. 5. Grimsley,
J. K.; Scholtz, J. M.; Pace, C. N.; Wild, J. R.; Biochemistry,
1997, 36, 14366-14374.
P 1.8
Osservazione
diretta
dell’effetto
dell’associazione con la base complementare sul
potenziale di ossidazione di guanosina e
adenosina
Amedeo Capobianco a, Tonino Carusoa, Andrea Pelusoa
a
Dipartimento di Chimica, Università di Salerno, Via
Fisciano,
SA
Ponte
Don
Melillo,
I-84085
[email protected]
P 1.7
I potenziali di ossidazione di derivati della guanosina e
dell’adenosina e dei loro complessi a ponte idrogeno con
citidina e timidina sono stati determinati per via
voltammetrica in CHCl3 ed altri solventi organici.
Mn2+ in marmi bianchi antichi. Determinazione
della cava con spettroscopia EPR tramite
parametri magnetici
Alfonso Zoleo and Marina Brustolon
Dipartimento di Scienze Chimiche, Via Marzolo 1, 35131
Padova
La determinazione della cava di origine dei marmi
bianchi antichi richiede l’uso di tecniche complementari,
ma tra queste una delle più discriminanti è la
spettroscopia EPR applicata al catione di Mn2+ (S=5/2),
vicariante del Ca2+ e del Mg2+ nella calcite e nella
dolomite. Il dintorno del Mn2+ infatti risente delle
condizioni geochimiche di origine della cava, che
determinano la simmetria del dintorno e la disomogeneità
locale come segni identificativi della cava stessa.
Gli spettri EPR del Mn2+ nei
marmi
hanno
caratteristiche fenomenologiche che dipendono dalla
storia geochimica della cava. Grazie al database creato da
D. Attanasio [1], è possibile usare queste caratteristiche
(ampiezza dello spettro, distanze tra alcune coppie di
righe) per attribuire la cava di origine con un margine di
errore.
La simulazione numerica dello spettro, basata sui
parametri dell’Hamiltoniano di spin (parametri di Zero
Field Splitting, tensore di interazione iperfine, tensore
quadrupolare) permetterebbe una maggiore precisione
nella classificazione degli spettri rispetto all’osservazione
Per rendere solubili i nucleosidi in cloroformio, i gruppi
OH sugli zuccheri sono stati protetti con terz-butildimetil-silile.
In CHCl3, nel caso della guanosina, la formazione del
complesso tipo Watson-Crick con la citidina comporta un
abbassamento del potenziale di ossidazione di 0.34 V.1
Allo stesso modo il potenziale di ossidazione
dell’adenosina diminuisce di circa 0.28 V per effetto
dell’interazione con la timidina.
Le costanti di autoassociazione2 e quelle di formazione
dei complessi guanosina-citidina e adenosina-timidina
sono state ottenute da titolazioni NMR; i valori
determinati sono simili a quelli riportati in letteratura per
54
le sole nucleobasi.
In figura è riportato il voltammogramma ciclico di una
soluzione 1mM Guanosina – 1mM Citidina in CHCl3. Il
potenziale è riferito alla semicoppia ferrocene/ferrocinio.
spectroscopic behaviour and the interaction of OTA with
different CDs. Dissolution of OTA in different solvents
showed deviation of absorption and fluorescence maxima
and variation of fluorescence quantum yields and of its
detection limit. The presence of CDs influenced the
protonated/deprotonated OTA equilibrium, as well as the
toxin fluorescence intensity, depending from the nature of
the solvent.
1. Ringot D., Chango A., Schneider Y., Larondelle Y., ChemicoBiological Interactions. 2006;159:18-46.
2. R. Verrone, L. Catucci, P. Cosma, P. Fini, A. Agostiano, V.
Lippolis, M. Pascale, J. Incl. Phen. and Macrocyc. Chem.
2007;57:475-479.
Calcoli teorici basati sul modello di Buckingham3 in cui
le molecole interagenti sono rappresentate come multipoli
e polarizzabilità statiche e calcoli quantistici in cui la
base purinica è trattata a livello B3LYP e la base
pirimidinica è modellata come potenziale efficace di
frammento, mostrano che l’abbassamento del potenziale
di ossidazione della base purinica nel complesso è dovuto
principalmente
alla
polarizzazione
della
base
pirimidinica.
Infatti, la differenza tra il potenziale di ossidazione della
base purinica e quello del complesso purina-primidina
coincide con la variazione di energia di interazione del
complesso a ponte idrogeno per effetto della
ionizzazione.
P 1.10
Activity of photosynthetic membrane proteins of
Rhodobacter sphaeroides: a possible role of
cardiolipin
Vincenzo De Leoa, Lucia Catuccia,b, Francesco Milanob,
Angela Corcellib,c, Angela Agostianoa,b
a
Dip. di Chimica, Università di Bari, Via Orabona 4,
70126 Bari, Italy [email protected]
b
IPCF-CNR, Via Orabona 4, 70126 Bari, Italy
c
Dip. di Biochim. Medica e Biol. Medica, Univ. di Bari,
P.zza G. Cesare, 70124 Bari, Italy.
The levels of the anionic phospholipid cardiolipin have
been found to increase upon exposition of the cells of the
photosynthetic bacterium Rhodobacter sphaeroides to
ipertonic solutions [1]. It is known that physical and
chemical properties of the membrane proteins are
critically determinated by the lipid matrix in which they
are embedded. In the present work we performed
investigation on the cardiolipin content on the
photoactivity of chromatophores from Rhodobacter
sphaeroides cells upon osmotic shock treatment. The
presence of higher levels of cardiolipin enhances the
thermal stability and the resistance to QB-site inhibitors of
Reaction Centre in chromatophores, as indicated by
charge recombination kinetics recorded after flash
excitation. Moreover the resistance to photooxidative
damages of Reaction Centre seems that is affected by
cardiolipin content. Also the bc1 complex activity
increases in chromatophores obtained from osmotically
shocked cells, as well as the stability of antenna
complexes to alcohol-induced denaturation.
1. Caruso, T.; Carotenuto, M.; Vasca, E.; Peluso, A.; J. Am.
Chem. Soc., 2005, 127, 15040 – 15041.
2. Kyogoku, Y.; Lord, R. C.; Rich A.; J. Am. Chem. Soc., 1967,
89, 496 – 504.
3. Buckingham, A. D.; Adv. Chem. Phys., 1967, 12, 107 – 142.
P 1.9
Spectroscopic study of ochratoxin A and its
interaction with cyclodextrins
R. Verronea, L. Catuccia,b, P. Finib, P. Cosmaa,b, A.
Agostianoa,b, V. Lippolisc, M. Pascalec
a
Dip. di Chimica, Università di Bari, Via Orabona 4,
70126 Bari, Italy [email protected]
b
IPCF-CNR, Via Orabona 4, 70126 Bari, Italy
c
ISPA-CNR, Via G. Amendola 122/O, 70126 Bari, Italy
1. Catucci, L., Depalo, N., Lattanzio, V.M.T., Agostiano, A. and
Corcelli, A J.Biochem. 2004, 43, 15066-15072.
Ochratoxin A (OTA) is a mycotoxin produced by several
Aspergillus species and by Penicillium verrucosum. OTA
contaminates a wide range of foodstuffs, including
cereals and their derivatives, coffee, beer, wine and
cacao, and can represent a serious health threat both to
humans and animals1. OTA can be also found in meat
and milk because of carry-over by which the mycotoxin
contained in feedstuffs can resist to metabolic processes
and accumulate in the organism. It has been shown that
OTA is neprhotoxic, hepatotoxic, teratogenic and
immunotoxic to humans and several species of animals.
Previous studies demonstrated that the presence of
cyclodextrins (CDs) can affect OTA spectroscopic
properties2. The ability of CDs to form inclusion
complexes usually lead to variations in physico-chemical
properties of the guest molecule, mainly enhancement of
both solubility and fluorescence. In this work we
investigated the effect of solvent properties on OTA
P 1.11
Photosystem II thermal stability and pigment
photobleaching: Effect of membrane lipids
Andrea Ventrellaa, Lucia Catuccia,b, Giuseppe Mascolo,c,
Angela Corcellib,d, Angela Agostianoa,b
a
Dip. di Chimica, Università di Bari, Via Orabona 4,
70126, Bari, Italy. [email protected]. bIPCFCNR, sez. Bari, Via Orabona 4, 70126, Bari, Italy. cIRSACNR, sez. Bari, Via F. De Blasio 5, 70123, Bari, Italy.
d
Dip. di Biochim. Medica e Biol. Medica, Univ. di Bari,
P.zza G. Cesare, 70124, Bari, Italy.
55
Tale indagine è stata effettuata parallelamente all’analisi
strutturale e dinamica del complesso As-GSH effettuata
attraverso tecniche 1H- e 13C-NMR e calcoli teorici.
In this work, the effects of different exogenous
phospholipids on spinach Photosystem II (PSII) complex
activity were investigated: in particular, PSII thermal
stability and resistance to strong illumination, leading to
photobleaching, were studied in the presence of
cardiolipin (CL) and phosphatidylglycerol (PG) by
means of UV/Vis Absorption, Emission, Resonance Light
Scattering and Oxygen Evolution Rate measurements.
The phenomenon of PSII pigment photobleaching was
studied by observing not only the effects of different
phospholipids but also of other factors, such as the PSII
aggregation state (monomers and dimers were tested) and
the temperature. In both thermal stability1 and
photobleaching experiments, it was found that the
presence of PG or CL helped the PSII activity to be better
preserved.
Moreover, in order to gain information about the
phospholipids directly surrounding the PSII complex,
analyses of lipid extracts from spinach membrane
fragments enriched in PSII and from spinach PSII dimers
were carried out by means of Thin Layer
Chromatography and Electro-Spray Ionization Mass
Spectrometry. Isolation and characterization of CL found
in association with PSII were obtained by mass and massmass analyses and evidences of CL structures with four
unsaturated C18 acyl chains and variable saturation
degrees were pointed out for the first time.
1. Oremland, S. R., Stolz, J. F., Science, 2003, 300, 939 – 944. 2.
Harvey, C. F., et al.,. Science, 2002, 298, 1602 – 1606.
P 1.13
Investigation of Self-Assembling Ionic Peptides
M. Alderighia, C. Ducea, S. Montib, R. Solaroa, M.R.
Tinéa
a
Dept. of Chemistry & Industrial Chemistry, via
Risorgimento 35, 56126 Pisa, Italy. [email protected]
b
Istituto per i Processi Chimico-Fisici (IPCF-CNR),
Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa, Italy
The capability of self-assembling in situ into three
dimensional scaffolds under physiological conditions
together
with
the
biocompatibility
and
the
biodegradability are desirable features of biomaterials
useful for tissue engineering and drug delivery
applications.
The class of oligopeptides originally discovered by
Zhang et al. [1-2] exhibits these properties and they can
also be considered as a model system for studying
insoluble macrostructures, which have been found in
many neurological disorders such as Alzheimer diseases
[3].
This class of oligopeptides consists of alternating
hydrophilic and hydrophobic aminoacids; the hydrophilic
surface of the molecule is constituted by alternating
oppositely charged aminoacid residues. Several
applicative studies on these systems are reported in the
literature [1-3] but a systematic investigation of the
physical-chemical features of the aggregation process is
still lacking.
Central to mimicking biologically inspired self-assembly
is the understanding of the forces that govern the
thermodynamic stability and specificity of naturally
occurring self-assembly events. The challenge is to
rationally design building blocks amenable to selfassembly.
In this work, we investigate the self-assembly process of
some tripeptides and pentapeptides characterized by an
alternating sequence of negative and positive charges.
KEK, KER, and RDKDR oligopeptides are in both the
amidated (NH2-KEK-CONH2, NH2-KER-CONH2, and
NH2-RDKDR-CONH2) and acetylated-amidated (AcNHKEK-CONH2, AcNH-KER-CONH2, and AcNHRDKDR-CONH2) forms. A synergistic combination of
Molecular Dynamics (MD) simulations, Atomic Force
Microscopy (AFM), and Isothermal Titration Calorimetry
(ITC) was used.
A series of classical molecular dynamics (MD)
simulations were performed to investigate the
aggregation properties of the short ionic tripeptide (KEK)
in water solution [4]. The atomistic description of peptide
and water molecules was based on the AMBER force
field and the TIP3P water model. Possible aggregates
were identified on the basis of potential inter-peptide
hydrogen bonds and association/dissociation events were
evaluated considering hydrogen bonds lifetime. The
effects of different end groups on KEK peptide
conformational self-assembling characteristics were
evidenced through the analysis of structural microscopic
and macroscopic parameters of the sampled aggregates.
Ramachandran maps for the (φ,ψ) backbone dihedral
1. A. Ventrella, L. Catucci, G. Mascolo, A. Corcelli, A.
Agostiano,
BBA
Biomembranes
doi:10.1016/j.bbamem.2007.03.024
P 1.12
Studio sul metabolismo dell’arsenico attraverso
spettroscopia NMR in vivo.
Marianna Aggravia, Claudia Bonechia, Claudio Rossia,
Nadia Marchettinib, Enzo Tiezzib, Alessandro Donatia
a
Università degli Studi di Siena, Dipartimento di Scienze
e Tecnologie Chimiche e dei Biosistemi, Via Aldo Moro 2,
53100 Siena, Italia. [email protected]
b
Università degli Studi di Siena, Dipartimento di Scienze
e Tecnologie Chimiche e dei Biosistemi, Via della Diana
2/a, 53100 Siena, Italia.
Il tema dell’interazione tra arsenico e organismi viventi è
attualmente un argomento di intenso interesse scientifico.
Ciò è dovuto alla recente scoperta che questo elemento,
non sia caratterizzato solamente dalla sua ben nota
tossicità acuta, ma anche da una tossicità cronica che si
esplica anche a concentrazioni molto basse.
Il metabolismo dell’arsenico negli organismi viventi ha
delle caratteristiche molto interessanti che coinvolgono
variazioni cicliche del proprio stato redox, l’interazione
con i gruppi tiolici di molte biomolecole, tra cui il
glutatione (GSH) e l’emoglobina, e l’azione mimetica
rispetto al gruppo fosfato. Purtroppo, nonostante i
progressi fatti, il meccanismo di azione tossicologica non
è stato ancora completamente chiarito. Ad esempio non è
chiaro come l’arsenico venga trasportato all’interno delle
cellule, come si esplichi l’azione tossica dei suoi
metaboliti metilati e quale ruolo abbiano i processi redox.
Nel presente lavoro viene presentato uno studio NMR in
vivo che mette in luce il comportamento di As
nell’interazione con globuli rossi umani e di ratto, sia da
solo che in presenza di glutatione e di altre molecole
contenenti gruppi tiolici.
56
angles of the aminoacid residues and intramolecular as
well as intermolecular hydrogen bonds were recorded.
To obtain a quantitative estimate of the aggregate size
and shape, the ratio of the largest to the smallest principal
moments of inertia (rI = Imax/Imin), the eccentricity η=1Iave/Imax where Iave is the average of the three principal
moments of inertia, and the radius of gyration Rg, were
calculated.
AFM sample were prepared on mica by room
temperature casting peptide water solutions at
concentrations included between 6 µM and 5 mM. The
images were recorded in tapping mode by a Multimode
AFM Veeco instrument equipped with Nanoscope IV
controller by collecting both topography and phase
images.
AFM images of Ac–KEK–NH2 cast on mica from 6 µM
water solution showed the presence of 10–50 nm round
clusters. The number of aggregates appreciably increased
when 37 µM solution was used, although the aggregate
size was almost unchanged. In both cases, the cluster
height was about 5-10 Å, indicating that the aggregates
consisted of oligopeptide monolayers. When AcNH–
KEK–CONH2 concentration was increased to 118 µM,
50-250 nm globular clusters 5–20 Å thick were detected,
in agreement with the presence of multilayer aggregates.
Also the AFM images of NH2-RDKDR-COOH
pentapeptide cast from 1 mM solution evidenced the
presence of globular aggregates, although their size was
about 10 times bigger. On the other hand, images of the
pentapeptide cast from 5mM solution evidenced the
presence of a network of long branched fibrils about 50
nm wide and 2 nm thick (Fig. 1).
1. Zhang, S.; Holmes, T. C.; Lockshin, C.; Rich, A. Proc. Natl.
Acad. Sci. USA. 1993, 90, 3334–3338. 2. Zhang, S., Lockshin,
C.; Cook, R.; Rich, A. Biopolymers 1994, 34, 663–672. 3. Fung,
S. Y; Keyes, C.; Duhamel, J.; Chen, P. Biophysical Journal
2003, 85 (1),537–548. 4. Duce, C.; Monti, S.; Solaro, R.; Tine,
M. R. J. Phys. Chem. B. 2007, 111(5), 1165-1175.
P 1.14
Use of Cyclodextrins to Improve
Photostability of RB in Aqueous Solutions
the
P.Finia, A.E.Di Maurob, S.Rochirab, P.Cosmaa, b,
.Catuccia, b, M.Castagnolo b, , A.Agostianoa, b
a
Istituto per i Processi Chimico Fisici (IPCF) CNR, sez.
Bari, Via Orabona 4, 70126 Bari, Italy;
b
Dipartimento di Chimica, Universita’ di Bari, Via
Orabona 4, 70126 Bari, Italy
Rose Bengal (3’,4’,5’,6’- tetrachloro-2’- (2,4,5,7tetraiodo -6- hydroxy-3-oxo-3H-xanthen-9-yl)benzoic
acid, bis (sodium salt) is an alogenated xanthene widely
exploited in many different fields. Almost all applications
are based on the peculiar spectroscopic and
photochemical properties of this dye. RB is often used as
reagent for the production of singlet oxygen or reactive
radicals and as standard for the evaluation of the
quantum yield of singlet oxygen production of other
photosensitizers. Therefore RB is often used in medicine,
mainly in the photodynamic therapy to inactivate
microorganisms and cause photodamage to target tissues.
Other uses of RB in medicine are as photochemical tissue
bonding to stitch wounds and to heighten damaged
corneal and conjunctival cells. RB is also used for the
waste water treatment and in the studies on solar energy
conversion.
Major limits in applications are the high tendency of this
dye in solution to aggregate with a consequent impairing
of photoactivity and the necessity to prepare RB solutions
just before the use or to keep them in the dark to avoid
the photodegradation.
Our recent studies have shown that the presence in
solution of cyclodextrin can be an efficient strategy to
reduce the formation of aggregates. After a wide
characterization of the interaction between RB and
cyclodextrins in aqueous solutions [1-3], performed by
measurements of vis absorbance, induced circular
dichroism, calorimetry and electrochemistry, we have
extended our studies on the effects of cyclodextrins on
RB photostability in aqueous solutions. In this report we
show the results of the study performed using acyclodextrin, hydroxypropyl-a-cyclodextrin, three β
cyclodextrins
(hydroxypropyl- β-cyclodextrin, the
heptakis (2,6-di-O-metil)-β- cyclodextrin,the heptakis
(2,3,6-tri-O-metil)-βcyclodextrin)
and
the
hydroxypropyl-gcyclodextrin
at
a
constant
concentration. The obtained results indicate that the
photostability of RB/CD complexes does not depend only
on the stability of the formed complexes.
Fig. 1. AFM topography of NH2-RDKDR-COOH cast
from 1 mM (left) and 5 mM (right) water solutions.
Preliminary ITC experiments carried out in PBS buffer,
at pH 7.4, and 25°C agree with AFM results. The
calorimetric profile of tripeptide dilution curves revealed
that aggregation process is not cooperative. The low
cooperativeness causes the presence of protoaggregates
even in dilute solution and results in non sigmoidal
calorimetric dilution curve. On the contrary the
enthalpogram of the pentapeptide AcNH-RDKDRCOOH shows a sigmoidal curve (Fig. 2) centered at 2.5
mM thus indicating the presence of a cooperative
transition.
1. P.Fini, M.Castagnolo, L.Catucci, P.Cosma, A.Agostiano,
Thermochimica Acta 418 (2004) 33.
2. P.Fini, F.Longobardi, L.Catucci, P.Cosma, A.Agostiano,
Bioelectrochemistry 63 (2004) 107.
3. P.Fini, R.Loseto, L. Catucci, P. Cosma and A.Agostiano, ,
Bioelectrochemistry (in press)
Figure 2. ITC enthalpogram of dilution of 12 mM AcNHRDKDR-COOH solution in pH 7.4 PBS.
57
Gies e collaboratori, che ne hanno ipotizzato la struttura
in base a misure di diffrazione (raggi X e neutroni), e a
misure NMR: un aspetto determinante è costituito dalla
presenza di network di legami idrogeno tra gli anioni
silossano, i gruppi silanolici superficiali e le acque di
solvatazione degli ioni Na+.
In questo lavoro la struttura proposta in letteratura è stata
verificata e dettagliata con un'analisi combinata
sperimentale e teorica. Gli spettri IR di campioni di
RUB18 sono stati accuratamente misurati a varie
temperature, e confrontati con gli spettri simulati da
calcoli ab initio ad alto livello; il confronto degli spettri
simulati e misurati ha permesso di discriminare tra
diverse possibili strutture atomiche delle regioni
superficiali, e di identificare i più probabili network di
legami idrogeno.
I calcoli teorici sono stati effettuati ottimizzando la
struttura tridimensionale del RUB18 a livello
semiempirico, selezionando la porzione più interessante
della superficie e ricavandone un cluster finito: la
struttura del cluster e lo spettro IR sono stati calcolati a
livello DFT con un funzionale ibrido e un set di base
esteso; l'effetto degli atomi più lontani è stato inserito nel
calcolo con tecniche miste di tipo QM/semiempirico. Il
livello della simulazione (e l'affidabilità dei risultati) sono
tra i più alti disponibili con le tecniche di calcolo attuale.
Il buon accordo tra gli spettri sperimentali e teorici
dimostra la correttezza del modello adottato: si è anche
dimostrato che è necessario considerare l'anarmonicità
del potenziale di stretching e la presenza di risonanze di
Fermi (tra la frequenza di stretching fondamentale e
armoniche superiori o combinazioni di frequenze più
basse) per assegnare correttamente gli assorbimenti legati
al network di legami idrogeno.
P 1.15
Studio del meccanismo di degrado di vetri
antichi rinvenuti nel parco archeologico di
Siponto (Foggia)
A. Gengaa, M. Sicilianoa, L. Famàa, D. Mannoa, T.
Sicilianoa, A. Mangoneb, A. Trainib, C. Laganarac
a
Dipartimento di Scienza dei Materiali, Università del
Salento, via per Arnesano 73100 Lecce Italy, e.mail
[email protected]
b
Dipartimento di Chimica, Università degli Studi di Bari,
via Orabona 4, 70126 Bari Italy
c
Dipartimento di Beni Culturali, Università degli Studi di
Bari, P.zza Umberto, 70100 Bari Italy
Durante gli scavi archeologici vengono rinvenuti
molti oggetti di interesse storico artistico caratterizzati
dalla presenza di strati superficiali di corrosione. Il futuro
stato di conservazione dipenderà dalle condizioni
individuali di conservazione (p.e. umidità, temperature,
concentrazione degli inquinanti atmosferici) e dalla
conoscenza dei parametri chimico-fisici che influenzano i
meccanismi di corrosione (p.e. cambiamento della
composizione superficiale, stabilità chimica, meccanismi
di lisciviazione e prodotti di alterazione).
Il degrado degli oggetti vitrei rinvenuti negli scavi
archeologici è un processo molto complesso; dipende sia
dalle caratteristiche chimico-fisiche dei vetri in oggetto
(composizione chimica, trattamenti termici, morfologia
superficiale) sia dalle condizioni esterne (microclima,
temperatura, pH, composizione della soluzione acquosa,
area superficiale per unità di volume del vetro in contatto
con il suolo). Nel caso di reperti archeologici antichi gli
strati di degrado possono avere spessore dalle decine di
micron fino a 100 µm e presentano un effetto di
iridescenza dovuti alle diverse proprietà ottiche degli
strati superficiali e del bulk.
In questo studio vengono presentate le indagini
preliminari sui meccanismi di degrado evidenziati in un
gruppo di 16 campioni datati XII provenienti dalla stessa
unità stratigrafica e rinvenuti nel parco archeologico di
Siponto.
P 1.16
Uno studio combinato spettroscopico-teorico
della struttura dell'ottasilicato di sodio RUB18
M. F. Iozzi, M. Cossi, C. Bisio, T. R. Macedo, L.
Marchese
Università del Piemonte Orientale, Dipartimento di
Scienze e Tecnologie Avanzate (DISTA), via Bellini 25G,
15100 Alessandria; [email protected]
1. Vortmann, S.; Rius, J.; Siegmann, S.; Gies, H. J. Phys. Chem.
B. , 1997, 101, 1292-1297
2. Borowski, M.; Kovalev, O.; Gies, H.; Microporous &
Mesoporous Materials, in press
I silicati stratificati (layered silicates, LS) riscuotono un
interesse crescente grazie alla loro elevatissima area
superficiale, che li rende utili come materiali di
stoccaggio e di scambio in numerose applicazioni
industriali: le proprietà chimico-fisiche delle superfici
sono dominate dalla natura idrofobica/idrofila, dalla
capacità di scambio ionico, e dalle proprietà molecolari
conferite dagli adsorbiti organici con cui i silicati sono
modificati. Benché la conoscenza della struttura dei LS a
livello atomico sia di primaria importanza per
interpretarne il comportamento, molte di queste strutture
sono ancora sconosciute.
In particolare, l'ottasilicato RUB18 [Na8Si32O64(OH)8 *
32H2O] è stato recentemente analizzato dal gruppo di
58
All these results that represent a new approach
in the elucidation of the problem of protein selfassembling could be of extreme importance for the
clarification of the mechanism of amyloid aggregation.
P 1.17
Influence Of Crowded/Confined Environments
On Dynamics Of Amyloidogenic Protein SelfAssenbling
This work is supported by Project EU-NMP-STRP
032652 BIODOT.
A. N. Lazar, E Bystrenova, C. Dionigi, P. Greco, S.
Dutta, P. Stoliar, M.G. Cacace and F. Biscarini
CNR, ISMN-Istituto per lo Studio dei Materiali
Nanostrutturati,Via P. Gobetti 101, 40129 Bologna, I T A
L Y, [email protected]
[1] Ferrone F, Methods Enzymol. 1999, 256-74
[2] Uversky VN, Fink AL., Biochim Biophys Acta, 2004, 13153
[3] Schladitz C, Vieira EP, Hermel H, Mohwald H., Biophys J.,
1999, 3305-10
[4] Giacomelli CE, Norde W., Macromol Biosci., 2005, 401-7
[5] Walsh DM, Tseng BP, Rydel RE, Podlisny MB, Selkoe DJ.,
Biochemistry., 2000, 10831-9.
Proteins are the main essential active agents in
biology and their geometrical characteristics are
determinant for their functioning. Changes of the tertiary
structure of proteins is known to have critical effect on
functioning of cells and proteins self-assemblies are
involved in a series of diseases like Alzheimer, Mad cow,
Cystic fibrosis and even some types of cancers1.
A complete understanding and control of the
kinetics of the modifications in the tertiary structures of
proteins under crowded/confined conditions may give the
crucial information for developing efficient therapies or
even for early diagnostic.
We propose new alternatives for understanding
the dominant forces governing aggregation kinetics of
amyloidogenic proteins2 in crowded/confined
environment – that mimics the dense environment in a
living cell.
First of all we show that the characteristics of
the environment like charge and hydrophilicity of
substrates3, molecular crowding associated to the
macromolecules, are substantial parameters influencing
the dynamic and self-structuring of the proteins.
Secondly, an evaluation of the aggregation
mechanism of proteins4,5 in a confined environment and
not in a bulk continuous aqueous environment was
performed. We succeeded in obtaining well-organized
self-assemblies of proteins, with different characteristics
(shape, molecular mass, tendency to aggregate) by the
use of confined environments (bi-dimensional nano- and
micro-channels and three dimensional cavities). This
approach enables the understanding of the constrainshape environment on proteins self-organization.
P 1.18
Studio strutturale del processo di “unfolding”
dell’albumina umana
Claudia LEGGIO, Luciano GALANTINI, Nicolae Viorel
PAVEL
Dipartimento di Chimica, Università La Sapienza, P.le A.
Moro 5, 00185 Roma, [email protected]
Le malattie da condensazione sono patologie eterogenee
fra di loro ma caratterizzate da una iniziale perdita di
solubilità di sostanze specifiche e da una conseguente
formazione di fasi condensate [1]. Esempi tipici di tali
malattie sono i calcoli renali, la cataratta, le nefriti, alcune
patologie reumatiche, che sono spesso dovute alla
denaturazione, all’aggregazione ed alla conseguente
precipitazione di proteine. Poiché le molecole che
condensano sono spesso proteine, gli agenti
antidenaturanti potrebbero essere dei buoni candidati per
il trattamento di queste malattie. La denaturazione delle
proteine, seguita dal processo di aggregazione, può
avvenire in fenomeni di infiammazione cronica in vivo.
La denaturazione dell’albumina è stata osservata in
pazienti con patologie reumatiche o lesioni
infiammatorie. Per questo la stabilizzazione delle
proteine in vivo è un problema di estrema rilevanza
fisiologica. Molte sostanze esogene ed endogene
proteggono le proteine dalla denaturazione. In questo
senso ci sono numerose indicazioni di un effetto benefico
della stabilizzazione delle proteine nel processo
reumatico [2].
Nel nostro laboratorio è in corso uno studio mirato a
determinare una correlazione tra la struttura e la stabilità
dell’ albumina di siero umano (HSA) in presenza di
agenti endogeni ed esogeni. Sono stati effettuati studi
preliminari (diffusione di raggi X a piccoli angoli,
diffusione sia statica che dinamica della luce, misure di
dicroismo circolare e di fluorescenza) allo scopo di
discriminare la struttura dell’HSA monomerica
e
parzialmente denaturata dalla forma aggregata. Per
quanto riguarda il processo di “unfolding”, vi sono
numerosi lavori con risultati in contrasto tra loro. Alcuni
parlano della presenza di due soli stati, proteina nativa e
denaturata, mentre studi più recenti prevedono la
presenza di uno stato intermedio. Kamal et al. [3] hanno
studiato la denaturazione dell’HSA a varie concentrazioni
di guanidina, mediante misure di idratazione dinamica ed
hanno proposto un possibile schema di apertura della
proteina con la presenza di uno stato intermedio, nel
quale rimane intatto esclusivamente il primo dominio.
Sono state quindi effettuate misure SAXS, SLS e DLS
a
b
c
Figure 1: AFM images of self-assemblies of betaamyloid peptide under different conditions: a – fibrils
formed in bulk crowded environment; b,c – oligomers
and fibrils formed in shape-constricted environments
59
per ottenere informazioni sulla conformazione che
l’albumina assume all’aumentare della concentrazione di
guanidina. Il grado di “unfolding” è stato monitorarto
mediante misure di dicroismo circolare e di fluorescenza.
I profili di intensità diffusa sono stati analizzati mediante
la Trasformata di Fourier [4]. Inoltre, programmi basati
su metodi statistici, quali il metodo Monte Carlo e
algoritmi genetici [5, 6], consentono di ottenere una
rappresentazione tridimensionale a bassa risoluzione
delle diverse conformazioni che la proteina assume al
variare della concentrazione di guanidina. I risultati
mostrano che nel processo di “unfolding” sono presenti
stati intermedi.
P 1.20
ATPasi di tipo P in modelli di membrane
biologiche: studio delle proprietà funzionali
M.R. Moncelli, G. Bartolommei, F. Tadini-Buoninsegni
Dipartimento di Chimica, Università di Firenze,
BioElectroLab, via della Lastruccia 3, 50019 Sesto
Fiorentino (FI); [email protected]
Nel nostro laboratorio si studiano da diversi anni proteine
di membrana in modelli sperimentali di membrane
biologiche. In modo particolare si studiano ATPasi di
tipo P con metodi chimico fisici. Recentemente abbiamo
focalizzato la nostra attenzione sullo studio delle
interazioni della Ca-ATPasi e della Na,K-ATPasi con
alcuni farmaci.
Si illustreranno:
- le caratteristiche generali delle ATPasi;
- i metodi di indagine utilizzati: a) spettrofluorimetria con
sonde stiriliche elettrocromiche e b) tecnica per salti di
concentrazione su SSM (Solid Supported Membrane) [12].
Si presenteranno alcuni risultati:
- interazione della Ca-ATPasi con inibitori a differente
affinità
(clotrimazolo
[3],
tapsigargina,
acido
ciclopiazonico, curcumina);
- interazione della Na,K-ATPasi con clotrimazolo.
1. J. D. Sipe, A. S. Choen, J. Struct. Biol., 130, 88 (2000).
2. L. Saso, B. Silvestrini, Medical Hypotheses, 56, 114 ( 2001).
3. J. K. A. Kamal, L. Zhao, A. H. Zewail, Proc. Natl. Acad Sci.
USA, 101, 13411 (2004).
4. O. Glatter, J Appl. Cryst., 10, 415 (1977).
5. P. V. Konarev, M. V. Petoukhov, V. V. Volkov, D. I.
Svergun, J. Appl. Cryst., 39, 277 (2006).
6. W. T. Heller, J. K. Krueger, J. Trewhella, Biochemistry, 42,
10579 (2003).
P 1.19
1. Tadini-Buoninsegni, F.; Bartolommei, G.; Moncelli, M.R.;
Inesi, G.; Guidelli, R.; Biophys. J., 2004, 86, 3671-3686. 2.
Tadini-Buoninsegni, F.; Bartolommei, G.; Moncelli, M.R.;
Guidelli, R.; Inesi, G.; J. Biol. Chem., 2006, 281, 37720-37727.
3. Bartolommei, G.; Tadini-Buoninsegni, F.; Hua, S.; Moncelli,
M.R.; Inesi, G.; Guidelli, R.; J. Biol. Chem., 2006, 281, 95479551.
Stabilità termodinamica del multimero del
telomero umano ed energetica dell’interazione
con la porfirina cationica
Luigi Petracconea, Luigi Martinoa, Bruno Paganob,
Guido Baronea, Concetta Giancolaa
a
Dipartimento di Chimica, Università di Napoli
“Federico
II”,
via
Cintia,
80126
Napoli,
[email protected]
b
Dipartimento di Scienze Farmaceutiche, Università di
Salerno, via Ponte Don Melillo, 84084 Fisciano
P 1.21
Il DNA telomerico umano, situato all’estremità dei
cromosomi, termina con la sequenza nucleotidica
d(TTAGGG), ripetuta n volte1. Questa sequenza, che in
parte si presenta come un singolo filamento, è in grado di
formare strutture a quadrupla elica di DNA. Queste
strutture sono di particolare interesse per il loro ruolo
biologico e come possibili target di molecole di interesse
farmacologico implicate nella terapia anticancro. La
maggior parte degli studi sulle proprietà termodinamiche
e cinetiche della formazione delle G-quadruplex e delle
loro interazioni con molecole di interesse farmacologico,
sono stati condotti sulla sequenza telomerica umana
formata da sole quattro unità ripetitive, d(TTAGGG)4.
Sono necessari, quindi, ulteriori studi per caratterizzare le
proprietà di sequenze più lunghe di DNA telomerico
(costituito da un numero di unità ripetitive superiore a
quattro). Tali studi permetteranno di stabilire se i dati
raccolti sulla sequenza telomerica corta sono utili per
predire le propriertà della sequenza più lunga. A tal fine,
è qui riportata la caratterizzazione sia della stabilità
termodinamica che dell’energetica dell’interazine con la
porfirina, della sequenza telomerica umana con otto unità
ripetitive, d(TTAGGG)8. I risultati sono stati confrontati
con quelli ottenuti sulla sequenza telomerica corta
d(TTAGGG)4. Lo studio è stato condotto mediante
tecniche
microcalorimetriche
(DSC,
ITC)
e
spettroscopiche (CD).
Direct micelles as microreactors for the tuning
of cobalt ferrite nanoparticle sizes
A. Ardua, C. Cannasa, A. Musinua, D. Peddisa,
G.Piccalugaa, D. Gatteschib, C. Sangregoriob
a
Dipartimento di Scienze Chimiche, Cittadella
Universitaria di Monserrato, bivio per Sestu, 09042
Monserrato (Cagliari), Italy. [email protected]
b
Dipartimento di Chimica - Università di Firenze
Via della Lastruccia, 3, 50019 Sesto F.no
Synthesis and processing of fine magnetic
particles have been the subject of extensive research due
to their many technological applications including
ferrofluids,1 data storage2 and biomedicine.3 Most of
these applications require particles of uniform size and
shape distribution. In addition, for any particular
application the magnetic nanoparticles must possess
specific properties. For example, data storage
applications require particles with stable, switchable
magnetic states to represent bits of information, states not
affected by temperature fluctuations. In biomedical
applications,
the
nanoparticles
must
exhibit
superparamagnetic behaviour at room temperature. A
variety of methods have been developed to prepare these
nanoparticles, however in most cases the resulting
particles are poorly crystalline and calcination at high
temperature is needed to induce highly crystalline
structures.
1. Zakian, V. A.; Science, 1995, 270, 1601 – 1607.
60
Direct micelles (oil in water micelles) represent
a good and quite simple method for synthetize magnetic
crystalline nanoparticles with tunable particle size.4 The
microenvironment provides a template effect that controls
the size and the particle shape. Cobalt (II) and iron (II) or
iron (III) cloride and sodium dodecylsulphate (SDS) as
surfactant are used as precursors for the formation of
Co(DS)2, Fe(DS)2 or Fe(DS)3. CH3NH3OH is added to
the mixed micellar solution to induce the precipitation of
nanosized magnetic particles. The size of the crystalline
particles is controlled either by changing the micellar
concentration or by increasing the temperature from 50 to
80°C. The effect of the surfactant concentration, in the
investigated range, seems to be negligible.
In contrast to what is obtained with
conventional precipitation method from homogeneous
solution, cobalt ferrite particles can be obtained when the
synthesis is performed at very low reactant concentration
and at low temperature. Furthermore, when the synthesis
is performed using Fe(II) salt as reactant, nanoparticles
are obtained by micellar method whereas particles in the
micrometer range are formed by homogeneous solution.
P 1.22
Analisi termodinamica dell’interazione tra
ligandi e quadruple eliche del DNA telomerico
umano
Bruno Paganoa, Antonio Randazzob, Gary N. Parkinsonc,
Carlo A. Mattiaa, Concetta Giancolac
a
Dipartimento di Scienze Farmaceutiche, Università di
Salerno, via Ponte Don Melillo, 84084 Fisciano,
[email protected]
b
Dipartimento di Chimica delle Sostanze Naturali,
Università di Napoli “Federico II”, via D. Montesano
49, 80131 Napoli
c
The School of Pharmacy, University of London, 29-39
Brunswick Square, WC1N 1AX London
d
Dipartimento di Chimica, Università di Napoli
“Federico II”, via Cintia, 80126 Napoli
Il DNA telomerico degli eucarioti è una doppia elica
contenente brevi sequenze oligonucleotidiche identiche,
ripetute migliaia di volte in tandem. Le sequenze ripetute
del DNA telomerico variano a seconda degli organismi,
ma in tutte si riscontra la presenza di un elevato numero
di guanine. Inoltre, la parte 3’-terminale si presenta
sempre come un singolo filamento in grado di ripiegarsi
per formare inusuali strutture a quattro filamenti, le
quadruple eliche.1 Le quadruple eliche sono formate da
unità strutturali dette G-tetradi, in cui quattro basi coplanari di guanine si dispongono secondo uno schema
ciclico in cui ogni base accetta e dona
contemporaneamente due legami idrogeno. La
formazione delle quadruple eliche inibisce l’attività della
telomerasi, suggerendo un loro potenziale utilizzo nella
terapia anti-cancro. Diverse molecole si sono mostrate in
grado di legare e stabilizzare questa struttura in vitro,
amplificandone l’azione antitelomerasica.2
In questo studio è stata affrontata l’analisi chimico-fisica
dell’interazione tra le quadruple eliche formate dalla
sequenza ripetuta d(TTAGGG) del DNA telomerico
umano ed alcune molecole di interesse farmacologico
quali la distamicina e la porfirina cationica. I parametri
termodinamici associati all’interazione tra le quadruple
eliche di DNA ed i ligandi sono stati determinati, in
maniera diretta, mediante calorimetria isoterma a
titolazione (ITC). L’ITC ci ha permesso di studiare in
dettaglio i processi che portano alla formazione dei
complessi, ed inoltre, ci ha consentito di ripartire
l'energia libera di legame nelle componenti entalpiche e
entropiche, in modo da poter rivelare la natura delle forze
che guidano la reazione.
Figure: HRTEM of CoFe2O4 obtained form Fe(III)
precursor.
Transmission electron microscopy in low and high
resolution (figure) reveals that the particles are nanocubes
with a narrow particle size distribution and average
particle size ranging from 3 to 27 nm depending on the
iron salt used, concentration and temperature. X-ray
diffraction results indicate the typical spinel structure of
CoFe2O4 and show the structural evolution as a function
of temperature: cobalt ferrite phase is stable up to 1000°C
and the particle size increases gradually up to 700°C and
swiftly at higher temperatures.
1. Neidle, S.; Parkinson, G. N.; Curr. Opin. Struct. Biol., 2003,
13, 275 – 283. 2. Cuesta, J.; Read, M. A.; Neidle, S.; Mini Rev.
Med. Chem, 2003, 3, 11 – 21.
Mössbauer Spectroscopy and nitrogen physisorption
measurements are also performed in some specific cases
in order to study the kinetic of the cobalt ferrite formation
and the textural properties respectively. The materials are
found to exhibit superparamagnetism. The blocking
temperatures and coercivity are dependent on the size and
on the iron salt used during the synthesis.
P 1.23
Sintesi stereoselettiva di 1,2,3-triaril aziridine e
risoluzione strutturale via H1-NMR di derivati con
Pt(II)
E. Pindinelli, M. Fabio, L. Troisi
Università del Salento, Dipartimento di Scienze e
Tecnologie Biologiche ed Ambientali, via Monteroni,
73100 Lecce, [email protected]
1.Rosensweig, R.E.; Chem. Eng. Prog., 1989, 85,
53. 2.Alivisatos, P.; Science, 1996, 271, 933. 3.S.
O’ Brien, Nature, 2003, 423, 968-971. 4.Vestal,
C.R.; Zhang, Z.J.; J. Of Nanotec., 2004,Vol. 1, 240
L’elevata tenzione d’anello che caratterizza le aziridine
conferisce a questo eterociclo un’elevata importanza sia
61
nel campo della sintesi organica1, sia nel campo
farmaceutico2. Con questa comunicazione riportiamo la
sintesi stereoselettiva di alcuni 1,2,3-triaril aziridine
attraverso la metodologia di Darzens.
(244GHz) (3). The X-band spectrum of ABTS was
simulated with the program Bruker “X-Sophe” using a
Simplex type iteration. The other experimental spectra
were simulated using the program EasySpin (4) for fitting
solid state EPR spectra with anisotropic g- and hf-tensors
and for best fitting.
Experimental results were compared and discussed in the
frame of theoretical calculations based on density
functional theory (DFT) data. The agreement between
experimental and calculated data confirms that two
different routes of oxidations are possible for the two
different type of mediators.
An important role in determining the mechanism of
substrate oxidation may be played by the stability of the
oxidized form of the radical mediator, as well as by its
redox potential.
Ar
Ar
N
+
n-BuLi
Ar''
Cl
H
Ar'
N
THF, -78°C
Ar'
Ar2[Pt(II)]
Alcune di queste aziridine , in particolare quelle di
configurazione cis recanti sul C2 e C3 due eterocicli di
cui almeno uno dei due possiede un gruppo aza in
posizione α , si aprono nell’ambiente basico in cui viene
condotta la reazione, riarrangiando in una struttura
enamminica.
Saranno riportati i dati sulla stereoselettività della sintesi,
sulla stabilità dell’anello aziridinico e sulla
complessazione con il Pt(II) di alcune aziridine
simmetriche (Ar’=Ar’’) che ha permesso l’assegnazione
della
configurazione
cis/trans,
via
H-NMR
differenziando i protoni sul C2 e sul C3.
1.
2.
1. Galli, C.; Gentili, P.; J. Phys. Org. Chem., 2004, 17, 973-977.
2. Pogni, R.; Brogioni, B.; Baratto, M. C.; Sinicropi, A.;
Giardina, P.; Pezzella, C.; Sannia, G.; Basosi, R.; Biocat. and
Biotransf., 2007, in press.
3. Reijerse, E.; Schmidt, P.P.; Klihm, G.; Lubitz, W.; Appl.
Magn. Reson. in press.
4. Stoll, S.; Schweiger, A.; J. Magn. Reson., 2006, 178 (1), 4255.
Yudin A. K., Wiley-VCH: Weinheim,
Germany, Aziridines and Epoxides in Organic
Synthesis 2006.
Yudin A. K., and all, Acc. Chem. Res., 2006,
39, 194-206.
P 1.25
Membrane insertion and bilayer perturbation
by antimicrobial peptide
Sara Pistolesia, Jimmy B. Feixb, Rebecca Pognia
a
Dipartimento di Chimica, Università di Siena, Via A.
Moro, 53100 Siena, Italy, [email protected]
b
Department of Biophysics and National Biomedical EPR
Center, Medical College of Wisconsin, 8701 Watertown
Plank Rd., Milwaukee, Wisconsin 53226, U.S.A.
P 1.24
Evidence for different routes of oxidation in the
laccase-mediator system: a multifrequency EPR
and DFT study.
R. Pognia, B. Brogionia, A. Sinicropia, M. C. Barattoa, P.
Giardinab, G. Sanniab, R. Basosia
a
Chemistry Department, University of Siena, Via A.
Moro, 53100 Siena, [email protected]
b
Organic Chemistry and Biochemistry Department,
University of Naples, via Cinthia 4, 80126 Napoli
Antimicrobial peptides (AMPs) are an important
component of innate immunity, and have generated
considerable interest as a potential new class of antibiotic
(1-3). The biological activity of AMPs is strongly
influenced by peptide-membrane interactions, however
for many of these peptides the molecular details of how
they disrupt and/or translocate across target membranes
are not known. Our studies have focused on a linear,
synthetic hybrid composed of the first seven residues of
cecropin A and residues 2– 9 of the bee venom peptide
mellitin. This 15-residue peptide, designated CM15,
retains the two-domain structure of native cecropins (4),
with a highly cationic N-terminal region and a mostly
hydrophobic C-terminal region. CM15 displays potent,
broad-spectrum antimicrobial activity, yet lacks the
strong hemolytic activity of mellitin (5). Previously have
been shown that CM15 folds into an α-helix upon
membrane binding (6, 7), and that at low peptide/lipid
ratios (i.e., under initial binding conditions) the helical
axis is positioned ~ 5 Ǻ below the hydrophobic interface
of the membrane and aligned parallel to the bilayer
surface (6). Osmoprotection studies with live bacteria
indicate that cell killing by CM15 is mediated by the
formation of membrane pores with a diameter of 2.2 – 3.8
nm (8), however nothing is known about the intermediate
stages between initial binding and pore formation. In this
study we have used site-directed spin labeling (SDSL)
electron paramagnetic resonance (EPR) spectroscopy to
investigate the behavior of a spin-labeled analog of
CM15 as a function of increasing peptide concentration,
and utilized phospholipid-analog spin labels to examine
Laccases belong to the multicopper oxidase family and
catalyse the oxidation of a wide variety of organic
substrates with the concomitant reduction of O2 to water.
The use of low molecular weight compounds, called
mediators, in combination with laccase, makes the
enzyme suitable for the oxidation of “non-natural” nonphenolic substrates, hence significantly increasing the
number of chemical structures that can be degraded. The
role of the enzyme is to oxidise the mediator. The actual
oxidation of the substrate is then carried out by the
oxidized form of the mediator, in a non-enzymatic step.
Mediators act as co-substrates, shuttling electrons
between the enzyme and the substrate (1).
The understanding of the mechanisms of electron and
proton transfer and the insight on the interactions of
laccases with mediators can be of great help in designing
more
active
laccase-mediator
systems
for
biotechnological applications (2). In this view, we studied
the interaction between a fungal laccase, POXC from P.
ostreatus, and two chemically different redox mediators,
violuric acid (VIO) (–NOH type) and 2,2′-Azino-bis(3ethylbenzothiazoline)-6-sulfonic acid (ABTS). We
observed that a radical intermediate species was formed
on both synthetic mediators after the interaction with the
enzyme. Both radicals were investigated by
multifrequency EPR, X-band (9.4 GHz) and High Field
62
the effects of CM15 binding and accumulation on
physical properties of membrane lipids. We find that as
the concentration of membrane-bound CM15 is
increased, the N-terminal domain of the peptide becomes
more deeply immersed in the lipid bilayer. Peptide
binding dramatically increases interaction of the lipidanalog spin labels with the polar relaxation agent
NiEDDA, indicating that there are significant changes in
the physical state of the lipid bilayer that are not readily
detected by methods that examine motional dynamics
suggesting an increased permeability of the membrane to
polar solutes. There was no evidence of peptide-peptide
association, suggesting that transmembrane pores formed
by the peptide are either transient, or that individual
peptide monomers are separated by > 20 Ǻ. Binding of
CM15 to model membranes with a lipid composition
mimicking the bacterial inner membrane caused only
slight perturbations in membrane lipid dynamics, and
changes in lipid dynamics were observed only for
5PCSL, suggesting that CM15 remains in a region of the
bilayer near the hydrophilic interface even as the
concentration of bound peptide is increased. Accessibility
studies with both spin-labeled peptide and lipid-analog
spin labels indicated an abrupt structural change at a
lipid/peptide ratio of ~ 25:1. Overall, these results are
most consistent with the toroidal pore model as the
mechanism of bilayer disruption by CM15.
determinant wavefunctions) of the electronic and
equilibrium structure of the ground and excited states of a
molecule. Furthermore, the CASSCF wavefunction can
be readily used for subsequent multiconfigurational
second-order perturbation theory (2) computations
(CASPT2) of the dynamic correlation energy of each
state ultimately allowing for a quantitative evaluation of
energy gap between different electronic states. We show
that a quantum-mechanics/molecular-mechanics strategy
(3, 4, 5) based on ab initio (i.e. first principle)
multiconfigurational perturbation theory can reproduce
the spectral properties of a tryptophan residue in different
protein environments within few kcal mol-1. This result
gives access to a detailed understanding of the molecular
factors modulating the residue emission in different
proteins as well as in mutants. We also show that that the
same computational protocol can be used to simulate
protein embedded tryptophan neutral and cationic
radicals opening the way to the investigation of their
redox properties.
1. Boman, H.G.; Ann. Rev. Immunol., 1995, 13:61-92.
2. Hancock, R.E.W.; Chapple, D.S.; Antimicrob. Agents
Chemother., 1999, 43:1317-1323.
3. Zasloff, M.; Nature, 2002, 415:389-395.
4. Fink, J.; Merrifield, R.B.; Boman, A.; Boman, H.G.; J. Biol.
Chem., 1989, 264:6260-6267.
5. Andreu, D.; Merrifield, R.B.; Steiner, H.; Boman, H.G.;
Biochemistry, 1985, 24:1683-1688.
6. Bhargava, K.; Feix, J.B.; Biophys. J., 2004, 86:329-336.
7. Sato, H.; Feix, J.B.; Biochimica et Biophysica Acta., 2006,
1758(9):1245-56.
8. Sato, H.; Feix, J.B.; Biochemistry, 2006, 45:9997-10007.
Top. View of parvalbumine (left) and monellin (right)
highlighting the position of the 3-methylindole
fluorophore (red). Bottom. Structure of the fluorophore 3methylindole (in green).
1. Roos, B. O.; In Advances in chemical physics: ab initio
methods in quantum chemistry, Lawley, K. P., Ed. Wiley:
Chichester, UK, 1987; Vol. 2, pp 399-445.
2. Andersson, K.; Malmqvist, P.-Å. ; Roos, B.O. ; Sadlej, A.J. ;
Wolinsky, K.J.; Journal of Chemical Physics, 1990, 94, 54835488.
3. Coto P.B.; Strambi A.; Ferré N.; Olivucci, M.; Proc. Nat.
Acad. Sci. USA, 2006, 103, (46), 17154-17159.
4. Andruniów, T.; Ferré, N.; Olivucci, M.; Proc. Nat. Acad. Sci.
USA, 2004, 101, 17908-17913.
5. Sinicropi, A.; Andruniow, T.; Ferré, N.; Basosi, R.; Olivucci,
M.; J. Am. Chem. Soc., 2005, 127, 11534-11535.
P 1.26
The Fluorescence of Tryptophan in Monellin
and Parvalbumin Resolved at the ab initio
Multiconfigurational Perturbation Theory Level
Adalgisa Sinicropia, Sara Pistolesia, Rebecca Pognia,
Riccardo Basosia, Massimo Olivuccia,b
a
Dipartimento di Chimica, Università di Siena, via Aldo
Moro 2, I-53100 Siena, Italy
b
Chemistry Department, Bowling Green State University,
Bowling Green 43403, OH, U.S.A.
The computer-aided design of unnatural proteins with
specific optical properties, such as color and
luminescence, represent a complex problem. In these
cases, the quantum chemical method employed must be
capable to describe both ground and electronically
excited states of the protein chromophore. In particular,
the computational description of a luminescent (e.g.
fluorescent) protein implies the use of methodologies
capable to predict the excited state equilibrium structure
of fluorophores characterized, even for singlet states, by
mixtures of open-shell and charge transfer characters.
The ab initio (i.e. first-principle) complete-active-space
self-consistent-field (CASSCF) method (1) is a
multiconfigurational
method
offering
maximum
flexibility for an unbiased description (i.e. with no
empirically derived parameters and avoiding single-
P 1.27
Monitoring of the aggregation behaviour of a
catalytic protein targeted by anticancer drugs
through analysis of its intrinsic fluorescence
Stefania Ferrari1, Maria Paola Costi1, Monica Caselli2 and
Glauco Ponterini2
1
Dipartimento di Scienze Farmaceutiche and
2
Dipartimento di Chimica dell’Università di Modena e
Reggio Emilia,
via Campi 183, 41100 Modena,
[email protected]
THIS WORK IS PART OF THE LIGHTS (LIGAND TO
INTERFERE WITH HUMAN TS, LSHC-CT-2006-037852)
63
PROJECT (STREP FOUNDED BY THE
WWW.LIGHTS-EU.ORG.
FP6
findings are discussed.5 The adoption in the future of
rationally
designed
lipoplexes
stable
against
solubilisation by anionic lipids may allow increased
transfection
efficiency
of
lipoplexes.
PROGRAM)
Thymidylate synthase (TS) plays a key role in the
intracellular synthesis of thymine, a building block of
DNA. Its amount and activity depend on complex
biochemical paths that may in principle be controlled by
shifting the monomer (M) ↔ dimer (D) equilibrium in
the cellular environment.
+
==
hTS monomer-dimer equilibrium.
In view of the promising therapeutical implications of the
ability to control this equilibrium, we have been looking
for spectroscopic and photophysical observables able to
monitor M ↔ D interconversion of human TS.
In this contribution we will report on the results of
our analysis of the intrinsic fluorescence of human TS
and will show how such observables as emission and
excitation spectra, quantum yield, anisotropy and lifetime
distribution are affected by protein dimerization. A
molecular interpretation of the observed changes will be
finally attempted.
1. Felgner, P. L.; Ringold, G. M. Nature 1989, 331, 461-462.
2. MacDonald, R. C.; Ashley, G. W.; Shida, M. M.;
Rakhmanova, V. A.; Tarahovsky, Y. S.; Pantazatos, D. P.;
Kennedy, M. T.; Pozharski, E. V.; Baker, K. A.; Jones, R. D.;
Rosenzweig, H. S.; Choi, K. L.; Qiu, R. Z.; McIntosh, T. J.
Biophys. J. 1999, 77, 2612-2629.
3. Koynova, R.; Wang, L.; Tarahovsky, Y.; MacDonald, R. C.
Bioconjug. Chem. 2005, 16, 1335-1339.
4. Caracciolo, G.; Pozzi, D.; Caminiti, R., Marchini, C.;
Montani, M; Amici, A.; Amenitsch, H. Appl. Phys. Lett. 2006,
89, 233903-3.
5. Caracciolo, G.; Marchini, C.; Pozzi, D.; Caminiti, R.,
Amenitsch, H.; Montani, M; Amici, A. Langmuir 2007, 23,
4498-4508.
References:
Prasanna V. et al. Biochem. 1998, 37, 6883-93. ;
Lovelace L. L. et al. Biochem. 2007, 46, 2823-30
P1.28
P 1.29
Multicomponent
cationic
liposome/DNA
complexes: efficient vectors for gene delivery
Aspetti dinamici su scala macroscpopica
derivanti da organizzazione mesoscopica
G. Caraccioloa, D. Pozzia, R. Caminitia, C. Marchinib, M.
Montanib, A. Amicib, H. Amenitschc
a
Department of Chemistry, University of Rome “La
Sapienza”, P.le A. Moro 5, 00185 Rome, Italy.
b
Genetic Immunization Laboratory, Department of
Molecular Cellular and Animal Biology, University of
Camerino, Via Camerini 5, 62032 Camerino (MC), Italy.
c
Institute of Biophysics and Nanosystems Research,
Austrian Academy of Sciences, Schmiedelstrasse 6, A8042 Graz, Austria.
Grazia Biosa, Marcus Hausera, Sandra Ristorib, Eugenio
Simoncinic, Enzo Tiezzic e Mauro Rustici
Università di Sassari, Dipartimento di Chimica, Via
Vienna 2, 07100 Sassari, Italia
a
Otto-von-Guericke-UniversitÄat
Magdeburg,
Biophysics Group, UniversitÄatplatz 2, 39106
Magdeburg, Germany
b
Universitµa di Firenze, Dipartimento di Chimica, Via
della Lastruccia, 3, 50019 Sesto Fiorentino (FI), Italia
c
Universitµa di Siena, Dipartimento di Scienze e
Tecnologie Chimiche e dei Biosistemi, Pian dei
Mantellini 44, 53100 Siena, Italia
Cationic lipid/DNA complexes (lipoplexes) are the best
non viral carriers of DNA for gene delivery.1 Here we
report, for the first time, a synchrotron small angle X-ray
diffraction (SAXD) study aimed at clarifying the
correlation between transfection efficiency of lipoplexes
and the structural changes occurring when lipoplexes
interact with anionic membrane lipids (models of cellular
membranes).2-4 We showed that inefficient lipoplexes
were unstable, rapidly fused and released DNA upon
adherance to anionic vesicles. Conversely, formulations
that were found to be efficient as DNA vectors in mouse
fibroblast (NIH 3T3) and tumoral myofibroblast-like
(A17) cell lines resisted solubilisation even in strong
excess of anionic charge. These results implicate that
structural stability upon interaction with cellular anionic
lipids controls transfection efficiency of lipoplexes.
Possible molecular mechanisms explaining experimental
Le onde chimiche costituiscono degli esempi caratteristici
per molte reazioni in cui sono presenti processi
autocatalitici. Molti fenomeni come la propagazione di
onde chimiche, treni d'onda o spirali possono essere
descritte attraverso un meccanismo di reazionediffusione. Per esempio l'osservazione di geometrie
spiraliformi nei sistemi viventi ha importanti implicazioni
nella salute umana.
In questo lavoro focalizziamo la nostra attenzione sulla
caratterizzazione delle onde chimiche che si originano
nella reazione di Belousov-Zhabotinsky (BZ) in una
matrice fosfolipidica (DPPC). In questo caso la
64
propagazione di onde risulta influenzata dal contenuto di
lipidico presente nel mezzo di reazione. In soluzioni
acquose (0% DPPC) la reazione BZ conduce ad onde i
cui "tips" si muovono seguendo traiettorie tipo
"meandering" e la velocita di rotazione dell'onda
spiraliforme diminuisce linearmente con il contenuto di
DPPC nel mezzo di reazione in accordo con il generale
aumento della viscosità del mezzo.
In contrasto rispetto alla velocitµa di propagazione
dell'onda, altri parametri che descrivono le proprietµa
cinematiche della spirale presentano un comportamento
bimodale nel mezzo BZ/DPPC. La spirale ruota
rigidamente attorno ad un centro di circa 0.3 mm quando
la DPPC è compresa nell'intervallo tra 2.5 e 12% in peso,
mentre il diametro aumenta drasticamente quando il
contenuto fosfolipidico supera il 12%.
La dinamica del sistema che si osserva ad una scala
macroscopica riflette pertanto un organizzazione interna
originata a livello mesoscopico nei domini acquosi del
sistema acqua/lipide.
salt conditions. The obtained results suggest that the
superstructures building blocks can be an intermolecular
G-quadruplex structure, differently stabilized by Na+ and
K+
cations.
Surprisingly,
the
super-structural
organization of G-quadruplex blocks appears regulated
by the presence of negative phosphate charges at 5’
sequence termini.
Circular dichroism studies support both the presence of
intermolecular G-quadruplex and the different influence
of Na+ and K+ cations on their thermodynamic stability.
Possible molecular models are under investigation.
1. T. Marsh, J. Vesenka and E. Henderson. NAR (1995) 23, 696700
2. M. Batalia, E. Protozanova, R. Macgregor and D. Eric. Nano
Letters (2002) 2 269-274
3. L Rossetti, G. D’Isa, C. Mauriello, M. Varra, P. De Santis, L.
Mayol, and M. Savino: (submitted)
Mol .ellip. x10 -4
300
P 1.30
Superstructural Organization of a GQuadruplex
Forming
HomopuryneHomopyrimidine Tract belonging to the Human
Telomerase Reverse Transcriptase (H-Tert)
Gene Promoter.
a
200
100
0
-100
200
Maria Savinoa, Sabrina Pisanob, Michela Varrac,
Emanuela Michelia, Teresa Coppolac, Luciano Mayolc,
Pasquale De Santisb. aDipartimento di Genetica e
Biologia Molecolare and bDipartimento di Chimica,
Università di Roma “La Sapienza”. cDipartimento di
Chimica delle Sostanze Naturali Università di Napoli
“Federico II”.
[email protected]
250
300 320
Wavelength [nm]
Mol.ellip. x10-4
0
300
The G-quartets structure has been proposed over four
decades ago. In this arrangement four guanine can
associate in a cyclic bulding-block, held together via
Hoogsteen hydrogen bonds.
The G-quartets, in guanine-rich sequences, can organize
complex-folded structures, the so-called “quadruplexes”,
stabilized by monovalent cations.
The understanding of quadruplex structures closely
concerns two different research fields of increasing
interest: the biological significance of G-rich sequences
in genome organization and the development of
biomaterials for nanotechnology applications (1,2).
In our research group, recently, we analyzed the sequence
structural features of a homopurine/homopyrimidine
tract, located about 100 bp upstream of transcription site
within HTERT gene promoter, on account of its
importance in chromatin organization and in
transcriptional regulation (3).
Studying the structural organization of this homopurine
oligonucleotide,
(5’GGGGAGGGGAAGGAAAGG3’),HTP, by AFM
imaging, we have found out that it can organize linear
superstructures of different lengths on mica surface,
characterized by the recurrence of single elements spaced
every 14.2 nm. (See Fig.).
It is worth noting that the single units have height about
1.6 nm that are about twice with those of a duplex DNA,
used as standard.
To highlight the structures involved, we have carried out
electrophoretic mobility shift assays (EMSA) in different
0
200
b
0
100
00
-100
0
200
250
300
Wavelength [nm]
320
CD spectra of HTP
a) 50 mM NaCl, and 5 mM NaH2PO4 pH
7,5.
b) 50 mM KCl, and 5 mM KH2PO4 pH
7,5
P 1.31
Analisi Emergetica dell’impatto ambientale delle
faggete cedue lombarde
Alberto Schiraldi,, Thomas Epis
DISTAM Università di Milano, via Celoria 2 20133
Milano, [email protected]
Gli indicatori di di sostenibilità ambientale associata ad
un ciclo produttivo, ad un prodotto o ad un territorio sono
molti: Analisi del ciclo di vita (life cycle analysis).
•
Analisi eMergetica (eMergy analysis).
•
Impronta ecologica (ecological footprint).
•
Valutazione del capitale naturale e dei servizi degli
65
ecosistemi
(natural capital).
•
Analisi exergetica (exergy analysis).
•
Bilancio dei gas serra (greenhouse gas inventory).
•
Analisi di dati dal satellite (remote sensing).
•
Contabilità ambientale.
L’Analisi Emergetica si rifà alla memoria dell’energia
lungo la catena di trasformazioni e usi:
Nel bilancio emergetico compaiono i diversi ingressi
raggruppati secondo la tipologia che li identifica:
R: è stato considerata il solo input “Pioggia –
evapotraspirazione” poiché l’energia solare e il vento
sono i fenomeni che provocano la formazione delle
precipitazioni.
F: i termini propri dell’emergia acquistata sono suddivisi
in relazione alla tipologia.
Questa analisi richiede una procedura precisa:
1. Disegnare uno schema del sistema d’interesse
2. Definire i flussi emergetici tra i diversi elementi del
sistema.
3. Quantificare gli input in termini energetici, monetari
o di massa.
4. Determinazione dell’emergia di ciascun input,
ottenibile moltiplicando gli input per i
corrispondenti valori di transformity.
5. Somma dei singoli valori emergetici degli ingressi
(R + N + F) per ottenere il valore emergetico del
prodotto.
6. Calcolo della transformity del prodotto: emergia del
prodotto / unità del prodotto (j,g,$).
Lavoro
Macchinari
Capitali
F
I
Sole
Ecosistema
Forestale
Vento
Utilizzazioni
Forestali
Y
Pioggia
R
F
Per l’applicazione è stato utilizzato uno schema semplice
in accordo con altre valutazioni emergetiche forestali:
a) Emergy evaluation of boreal spruce (Picea abies)
and pine (Pinus silvestris) silvicultural production
and timber extraction under 80 year rotation
schedules in southern Sweden. (Doherty, 1995).
b) Emergy evaluation of slash pine (Pinus elliotti)
silvicultural production and timber extraction under
25 year rotation schedules in north Florida.
(Doherty, 1995).
c) Emergy evaluation fuelwood plantation production
(Eucalyptus spp. And Melaleuca spp.) under 5 tear
rotation schedules in south Florida. (Doherty, 1995).
Risorse
(ha/anno)
Energia solare
En. cinetica del vento
Pioggia- - evap
Carburante
Lubrificante
Macchinari forestali
Manodopera
Progettazione
Capitale investito
Transformity
(sej / unit)
1
1500
18200
47900
54000
6700000000
10900000
10900000
1500000000000
Applicata ad una faggeta cedua, l’analisi emergetica porta
ai seguenti risultati
Risorse
R
F
Y
Energia solare
En. cinetica del vento
Pioggia- - evap
Carburante
Lubrificante
Macchinari forestali
Manodopera
Progettazione
Capitale investito
Prodotto
Emergia
(sej /ha anno)
2,85988E+13
4,36379E+13
8,09172E+14
2,67382E+14
258336
2,16306E+13
2,55513E+14
3,06616E+13
7,96264E+13
1,46399E+15
Rapporto d'impatto ambientale, (N+F)/R = 0,809
Rendimento emergetico,Y/F = 2,236
Investimento emergetico, F/(N + R) = 0,809
66
self-assembling trans-annular nanotubes (or helical
channels) stabilized by multiple hydrogen bonds with
different inner radius and quantized lengths. These can be
further stabilized by suitably designed amino acid
sequences, which provide cross-links between the
adjacent cyclic DL-peptides (or helical spires).
On the basis of the theoretical predictions, more than
twenty years ago, long time before nanotubes were
conceived, we synthesized and investigated the properties
of poly(DL-proline) as an ion channel and found regular
current fluctuation events due to a single channel
molecule in bilayer membranes, doped with the
polypeptide (Figure 1) (2-5).
We are at present investigating the possibility to obtain
self-assembling nanotubes using different amino acids
and adopting suitable strategy of stabilization. In
particular, DL-cysteine and DL-lysine seem to be
promising. In fact, DL-cysteine could be stabilized by
vulcanization of adjacent annular peptides (Figure 2)
while DL-lysine nanotubes could be obtained by
formation of metal complexes between their
salycilaldimine derivatives (Figure 3) (7-8).
In all cases, it is possible to separate nanotubes with
differently sized lengths. Such nanotubes are
characterized by high rigidity and modularity and provide
the possibility to build ion single molecule conductors,
nanomemory for electronics obtained by the quantized
states of a suitable cation confined in a nanotube. Selfassembled nanotubes with peptide architecture can be
used for casting metal nanowires, for example to be used
as tips for Atomic Force Microscopy and improve the
resolution power. The peptide nanotubes coated with
suitable metal complexes of lysine derivatives are easily
oriented under magnetic field on suitable surfaces and
could be used as rigid linear building blocks for
spintronic devices.
P 1.32
Scuola Nazionale Di Metodologie Chimico
Fisiche Per Lo Studio Dei Sistemi Biologici
Alberto Schiraldi
DISTAM Università di Milano, via Celoria 2 20133
Milano, [email protected]
La Scuola Nazionale vuole essere un riferimento comune
per i gruppi di ricerca italiani che si occupano dello
studio di sistemi e sostanze di interesse biologico con
metodologie chimico-fisiche, sperimentali e teoriche.
La Scuola è rivolta a laureandi, dottorandi, borsisti,
ricercatori dell’università, degli enti pubblici e
dell’industria, che operano o intendono operare nel
campo delle scienze della vita. Le lezioni saranno
dedicate alla presentazione delle tecniche sperimentali e
degli aspetti teorici dello studio dei sistemi biologici, con
specifico riferimento alle macromolecole biologiche
(proteine, carboidrati, acidi nucleici) e alle strutture
supramolecolari di origine naturale e sintetica di interesse
fisiopatologico, farmacologico e alimentare.
La scuola si propone di trattare un ventaglio ampio di
tecniche Chimico-fisiche applicate ai sistemi biologici fra
le quali: NMR, EPR, Raman, Metodi ottici stazionari e
risolti nel tempo, Microscopia (AFM, STM, SNOM),
Metodi teorici e computazionali, Cristallografia a raggi X
(anche supportata da sorgenti al Sincrotrone),
Spettrometria di massa, Elettrochimica, Calorimetria, ecc.
la domanda di partecipazione dovrà essere inviata
all’indirizzo della segreteria [email protected].
La quota d’iscrizione è € 350.
Sono disponibili un numero limitato di borse di
partecipazione a copertura totale o parziale delle spese
d’iscrizione a favore di giovani non strutturati. Le
domande, corredate da una lettera di accompagnamento
del supervisore, dovranno pervenire alla Segreteria della
Scuola.
1. De Santis P.; Morosetti S.; Rizzo R.; Macromolecules, 1974,
7, 52-58. 2. De Santis P.; Palleschi A.; Savino M.; Scipioni A.;
Sesta B.; Verdini A.; Biophys. Chem., 1985, 21, 211-215. 3. De
Santis P.; Palleschi A.; Savino M.; Scipioni A; J. Phys. Chem.,
1988, 92, 4759-4765. 4. De Santis P.; Scipioni A.; Palleschi A.;
Savino M.; Biopolymers, 1989, 28, 285-296. 5. De Santis P.;
Palleschi A.; Scipioni A.; Camalli M.; Spagna R.; Zanotti G.;
Biopolymers, 1998, 45, 257-267. 6. Ascoli F.; De Angelis G.;
Del Bianco F.; Biopolymers, 1975, 14, 1109-1114. 7. Dentini
M.; De Santis P.; Savino M.; Macromolecules, 1980, 13, 13081311. 8. De Santis P.; Morosetti S.; Scipioni A; Journal of
Nanosciences and Nanotechnology, 2007, 7, 1-9 (invited paper).
P 1.33
Peptides with regular enantiomeric sequences as
self-assembling nanotubes for nanotechnology.
A. Scipionia, S. Morosettib, P. De Santisb
60 mV
a
Dipartimento di Chimica, La Sapienza Università di
Roma,
P.
le
A.
Moro5,
00185
Roma;
[email protected]
b
Dipartimento di Chimica, La Sapienza Università di
Roma, P. le A. Moro5, 00185 Roma
K+
1 pA
Fig.1
The wide interest in the nanoscience and nanotechnology
of carbon and inorganic nanotubes raised a renewed
attention to organic tubular assemblies. In fact, organic
trans-annular assemblies constitute an expanding class of
structures with promising applications in supramolecular
chemistry and realistic perspectives for the design of
nanotechnological devices for molecular electronics and
membrane separation technology. Among the strategies
developed for the design and engineering of organic
nanotubes, those characterized by regular alternating
enantiomeric amino acid sequences have been proven
particularly useful. The basic principles that regulate the
conformational stability of enantiomeric sequences were
formulated by De Santis and coworkers about thirty years
ago (1). Amino acid sequences with alternating
configurations have the propensity to form
Fig.2
67
P 1.35
Theoretical Studies on the Structure of
Polycyclic Aromatic Hydrocarbons (PAHs) and
Soot
Platelets
and
Their
Oxidative
Functionalization
Anna Giordana,a Andrea Maranzana,a Giovanni Ghigo,a
Mauro Causà,b G. Tonachinia
(a) Dipartimento di Chimica Generale e Organica A.,
Università di Torino, Corso Massimo D'Azeglio 48, I10125 Torino, Italy, e-mail: [email protected];
(b) Dipartimento di Chimica, Università di Napoli
"Federico II", ComplessoUniversitario di Monte
Sant'Angelo, Via Cintia 1, I-80126 Napoli, Italy
Fig.3
At the outset, we aimed to define appropriate PAH-like or
periodic models for a soot platelet, and then examined the
gas-solid interaction of some small species (H, NO, NO2,
and NO3) by which soot functionalization can take
place.[1] Subsequently, we considered soot oxidation
operated by ozone, and compared its features with some
experimental studies.[2] Finally, we have explored the
nature of the oxidized soot surface through the theoretical
study of the desorption mechanisms of a variety of polar
groups from different systems, and attempted to give a
contribution to the interpretation of Temperature
Programmed Desorption (TPD) spectra.[3]
P 1.34
Isotopic effect on the kinetics of the BelousovZhabotinsky
reaction:
Cerium-Malonic
subsystem.
Simoncini E.a, Rossi F.b, Rustici M.c, Marchettini N.a
a
Dipartimento di Scienze e Tecnologie Chimiche e dei
Biosistemi, via della Diana, 2/a, 53100 Siena.
[email protected]
b
Dipartimento di Chimica Fisica, Università di Palermo.
c
Dipartimento di Chimica, Università di Sassari, Via
Vienna 2, Sassari.
In this work we present results about the Deuterium
isotopic effect on Ce(IV) oxidation of Malonic Acid and
its influence on the global behaviour of the BelousovZhabotinsky reaction.
In the oscillating chemical reactions field the BelousovZhabotinsky (BZ) reaction, i.e. the catalytic oxidation of
Malonic Acid (MA) by bromate ions, in the presence of
ceric ions, represents one of the most known and studied
examples1,2. The study of the system in deuterated
environment allowed us to stress the relevance of the
enolization step in the bromine-MA reaction3.
The BZ reaction in deuterated environment presents a
slower global kinetics, as happens for the single Ce(IV) –
MA reaction4,5. In the present work, the kinetic constant
of MA oxidation by Ce(IV) in D2O was experimentally
calculated, and the reaction mechanism was
characterized. Furthermore, a BZ reaction simulation was
performed using MBM kinetic model and COPASI
package, introducing the kinetic constants found for
Ce(IV) – MA and bromine – MA reactions; we finally
compare simulation results with experimental data.
The investigation is now being extended to different
model systems, which can be reasonably assumed to form
during combustion. These are made up by an even or odd
number of carbon atoms, such as the PAH systems
detected in flames (where they are almost equally
important), and can contain 5-membered rings. For these
systems, we compare the reactivity of both internal and
peripheral positions toward ozone [4] as well as hydroxyl
and nitrogen oxides.[5,6]
1. Ghigo, G.; Maranzana, A.; Tonachini, G.; Zicovich-Wilson,
C. M.; Causà M. J. Phys. Chem. B 2004, 108, 3215–3223. 2.
Maranzana, A.; Serra, G.; Giordana, A.; Tonachini, G.; Barco,
G.; Causà M. J. Phys. Chem. A 2005, 109, 10929–10939. 3.
Barco, G.; Maranzana, A.; Ghigo, G.; Causà M.; Tonachini, G.
J. Chem. Phys. 2006, 125, 184706. 4. Giordana, A.; Maranzana,
A.; Ghigo, G.; Causà M.; Tonachini, G., to be submitted. 5.
Ghigo, G.; Causà M.; Maranzana, A.; Tonachini, G. J. Phys.
Chem. A 2006, 110, 13270-13282. 6. Maranzana, A.; Ghigo, G.;
Tonachini, G., to be submitted.
1. Belousov B. P.; Ref. Radiat. Med., 1959, 145. 2. Zhabotinsky,
A.; Biofizika, 1964, 9 (3), p. 306. 3. Rossi F.; Rustici M.; Rossi
C.; Simoncini E.; Tiezzi E.; 2006, XXII Congresso della Società
Chimica Italiana, Atti del Congresso, p. 249. Sessione Poster. 4.
Hsu M.-C.; Jwo J.-J.; Int. J. Chem. Kinet., 1999, 31, p.455-461.
5. Jwo J.-J.; Noyes R. M.; J. Am. Chem. Soc., 1975, 97, 54225431.
68
benzoic acid (s): lnP(kPa)=(15.52±0.38)–(10287±155)/(T/K)
P 1.36
(from 333 to 393 K)
Vapor pressures, sublimation and vaporization
enthalpies using isothermal and non-isothermal
thermogravimetry
benzoic acid (l): lnP(kPa)=(10.22±0.41)–(8130±141)/(T/K)
S. Vecchio
Dipartimento di Ingegneria Chimica Materiali Ambiente,
Sapienza, Università di Roma, Via del Castro
Laurenziano,
7,
00161
Roma,
[email protected]
naphthalene (s): lnP(kPa)=(13.41±0.46)–(8423±139)/(T/K)
(from 396 to 458 K)
ferrocene (s): lnP(kPa)=(11.50±0.45)–(8547±178)/(T/K)
(from 313 to 447 K)
(from 333 to 353 K)
The results obtained in this study confirm that
thermogravimetry offers several advantages over the
conventional techniques (Knudsen, torsion effusion, gas
saturation
and
transpiration
methods):
simple
experimental set-up, limited amounts of sample, short
time analysis, absence of pretreatment of the sample.
Even if its accuracy and precision are not so high
compared to the above-mentioned techniques it allows a
preliminary screening of the vapor pressure and a rapid
estimation of sublimation enthalpy of pure substances
[7,8].
Thermogravimetry under both isothermal and nonisothermal (linear heating) condition is used in this study
to determine apparent values of the vapor pressure of
pure substances. To this end, some substances whose
vapor pressures, vaporization and sublimation enthalpies
are known in suitable ranges of temperatures are
considered with the aim to test the reliability of the
method. The rate of mass loss, ∆m/∆t (kg s–1), due to free
evaporation under either isothermal and non-isothermal
conditions is correlated with the vapor pressure P (kPa)
exerted by the examined compounds tested, through the
Langmuir equation [1,2]:
1. Vecchio, S.; Brunetti, B.; J. Chem. Eng. Data, 2005, 50, 666 –
672. 2. Jones, H.A.; Langmuir, I.; Mackay, M.G.; Phys. Rev.,
1927, 30, 201 – 214. 3. De Kruif, C. G.; Blok, J. G.; J. Chem.
Therm. 1982, 14, 201 – 206. 4. Torres, L.A.; BarreiroRodriguez, G.; Galarza-Mondragon, A.; Thermochim. Acta
1988, 124, 229 – 233. 5. Sabbah, R.; Xu-wu, A.; Chickos, J. S.;
Leita, M. L. Planas; Roux, M. V.; Torres, L.A.; Thermochim.
Acta 1999, 331, 93-204. 6. Marsh, K. N.; IUPAC-Recommended
Reference Materials for the Realization of Physicochemical
Properties, Blackwell Scientific Publications, Oxford, UK, 1987.
7. Price, D.M.; Thermochim. Acta, 2001, 367-368, 253 – 262. 8.
Chatterjee, K.; Hazra, A.; Dollimore, D.; Alexander, K. S.; Eur.
J. Pharm. Biopharm., 2002, 54, 171 – 180.
∆ m 1
T  2 πR
⋅ ⋅
p = 
⋅ α′
S
M
∆t


where T is the temperature (K), M is the molar mass (kg
mol–1), R is the gas constant (R=8.3145 J mol–1 K–1) and
α' is the vaporization constant. Using a linear regression
analysis the enthalpies of vaporization and sublimation
were obtained from the slope of the modified ClausiusClapeyron plot ln[(∆m/∆t)·(1/S)·(T/M)0.5] vs. 1/T for the
two reference compounds at the mean temperature of the
experimental temperature range. These values were
subsequently corrected for the standard state at 298 K
using the difference Cp(g) – Cp(s) recommended from
literature [3,4]. The results obtained for benzoic acid and
ferrocene are reported in Tables 1 and 2, as an example.
(1)
P 1.37
Vaporization study of acetaminophen and three
of its derivatives using isothermal and nonisothermal thermogravimetry
Table 1 Molar standard enthalpies of benzoic acid
derived using the proposed TG techniques.
Literature enthalpy value for comparison purpose
is ∆subH°(298 K)=89.7±1.0 kJ·mol-1 (ref. 5).
V. Rossia, M. Tomassettib, S. Vecchioa
a
Dipartimento di Ingegneria Chimica Materiali
Ambiente, Sapienza, Università di Roma, Via del Castro
Laurenziano,
7,
00161
Roma,
[email protected]
b
Dipartimento di Chimica, Sapienza, Università di Roma,
P.le A. Moro, 5, 00185 Roma.
∆subH°(298 K)c,d
∆T
technique
process
K
kJ·mol-1
I-TG
sublim
333 – 356
87.7
± 1.5
NI&I-TGa
sublim
361 – 393
89.1
± 1.0
NI&I-TGaa
vaporiz
396 – 458
90.3
± 2.0
a
mean of three experiments (one I-TG and two NI-TG ones).
aa
mean of five experiments (one I-TG and four NI-TG ones).
The knowledge of vapor pressure is important in several
fields of application, ranging from the pharmaceutical
and the environmental to the separation and purification
ones. Even if thermogravimetry (TG) under both
isothermal and non-isothermal (linear heating) condition
is less accurate than conventional methods, it can be used
to determine apparent values of the vapor pressure of
pure substances with sufficient precision. On the other
hand, the relatively small amount of substance, the
simplicity of the experimental set-up and the short
experimental times represent the advantages of TG over
the more conventional techniques. Therefore, some
substances (whose vapor pressures, vaporization and
sublimation enthalpies are known in suitable ranges of
temperatures) can be considered to test the reliability of
the method. In the present study, benzoic acid, ferrocene,
and naphthalene were used for this purpose measuring the
rate of mass loss ∆m/∆t, due to free evaporation under
both isothermal and non-isothermal conditions through
the TG apparatus. This quantity can be correlated under
vacuum condition with the vapor pressure P exerted by
the examined compounds tested, through the Langmuir
Table 2 Molar standard enthalpies of ferrocene
derived using the proposed TG techniques.
Literature enthalpy value for comparison purpose
is ∆subH°(298 K)=89.7±1.0 kJ·mol-1 (ref. 5).
∆T
∆subH°(298 K)c,d
technique
process
K
kJ·mol-1
I-TG
sublim
313 – 353
73.6 ± 1.7
I-TG
sublim
396 – 436
74.1 ± 2.2
NI&I-TGa
sublim
357 – 403
73.7 ± 0.8
a
mean of three experiments (one I-TG and two NI-TG ones).
An excellent agreement was found between the obtained
molar standard enthalpies and those found in literature [5]
as well as those recommended by the IUPAC [6], thus
confirming the reliability of the proposed method.
Finally, the following average equations, which describe
the temperature dependence of vapor pressure, were
derived by applying a linear regression analysis to Eq
.(1):
69
equation [1]. Price and Hawkins [2] used this relation
with a TG equipment and affirmed that the vaporization
rate of the sample is not significantly affected by the flow
rate of the used purge gas. By contrast, Pieterse and
Focke [3] proposed a revised vaporization equation
justified by the fact that the rate of vaporization is limited
by diffusion. However, recently it was demonstrated
that in some cases the difference between the results
obtained using the two mentioned approaches is
negligible [4].
On the other hand, the atmospheric accumulation of toxic
compounds such as pesticides and pharmaceuticals is
essentially due to the use of substances having low vapor
pressure at room temperature [5]. Consequently, the
vaporization pathway of these substances is a crucial
phenomenon that is worth investigating. As far as
pharmaceuticals is concerned, their amount in a tablet
dosage form may vary due to evaporation during the
tableting process, hence depleting its specific properties
in the solid mixture.
Furthermore, for a given
formulation of a drug it is important to determine and
quantify the evaporation characteristics of each individual
component. To this end, in the present investigation
acetanilide and three of its para- substituted derivatives,
namely the para-hydroxyacetanilide (PHA), the paraethoxyacetanilide (PEA) and the para-bromoacetanilide
(PBA), were selected, taking into account that the thermal
behavior and the vaporization kinetics of these drugs was
already studied in a previous paper [6]. Moreover, in this
study their vaporization enthalpies as well as their
temperature dependences of vapor pressure were derived
over their melts in suitable ranges of temperatures using
both the methods proposed by Price and Hawkins [2] and
the one proposed by Pieterse and Focke [3]. The results
obtained were compared and discussed with a particular
view to establish if vaporization of these substances is
limited by diffusion. Furthermore, the experimental
vapor pressure data obtained in this study with both the
two methods for acetanilide were also compared with
those values reported in literature [7] in the same
temperature range.
In addition, the vaporization
enthalpies calculated at the mean of the experimental
temperature ranges were subsequently corrected for the
standard state at 298 K using the difference in the heat
capacity of solid and vapor proposed by Chickos et al [8].
In conclusion, the results obtained in this study enable us
to confirm that the TG technique is a useful tool to define
the vaporization characteristic of pure drugs with a
sufficient precision, providing a rapid response with a
small amount of sample and very short experimental time
compared with the conventional techniques used for this
purpose.
P 1.38
Monitoring peptide folding by Time-Resolved
Spectroscopies: the effect of a single Gly to Aib
susbtitution
Mariano Venanzi,a Emanuela Gatto,a Gianfranco
Bocchinfuso,a Antonio Palleschi,a Lorenzo Stella,a Chiara
Baldini,b Fernando Formaggio,b Claudio Toniolob and
Basilio Pispisaa
a
Department of Chemical Sciences and Technologies,
University of Roma Tor Vergata, 00133 Rome, Italy,
[email protected]
b
Department of Chemistry, University of Padua, 35131
Padua, Italy
We have recently reported1 on a new fluorescent
analog of trichogin GA IV, a natural peptide showing
interesting antimicrobial activity. The primary structure
(and acronym) of the peptide investigated is:
Fmoc-Aib-Gly-Leu-Aib-Gly-Gly-Leu-TOAC-GlyIle-Leu-OMe (F0T8)
The double substitution of an energy donor (Fmoc)
and an acceptor (TOAC) pair in the trichogin chain
enabled us to make use of time-resolved optical
spectroscopies, spanning from the nanosecond to the
microsecond time regime, to investigate the
conformational propensity and the dynamical features of
F0T8. Experimental and computational results indicated
that the structural and dynamical properties of F0T8 were
determined by the transition from an elongated helical
conformation to a compact structure mimicking a helixturn-helix motif. To further investigate the role of the
Gly5-Gly6 central motif we have synthesized a new
trichogin analog having the Gly6 residue substituted by
Aib, i.e.
Fmoc-Aib-Gly-Leu-Aib-Gly-Aib-Leu-TOAC-GlyIle-Leu-OMe (F0A6T8)
Time resolved spectroscopy measurements show that
the conformations actually populated by F0T8 are not
significantly perturbed by the Aib vs. Gly substitution in
F0A6T8, as also confirmed by preliminary molecular
mechanics calculations. This finding emphasizes the
structural rigidity of the peptides investigated. By
contrast, the Aib insertion affects the peptide dynamical
properties in the microsecond time scale. Important
differences in the binding of Ca(II) and Gd(III) by the
two peptides have been also observed.
1
M.Venanzi, E. Gatto, G. Bocchinfuso, A. Palleschi, L.
Stella, C. Baldini, F. Formaggio and C. Toniolo J. Phys. Chem.
B 2006, 110, 22834-22841.
1. Jones, H.A.; Langmuir, I.; Mackay, M.G.; Phys. Rev., 1927,
30, 201 – 214. 2. Price, D.M.; Hawkins, M.; Thermochim. Acta,
1998, 315, 19 – 24. 3. Pieterse, N.; Focke, W. W.; Thermochim.
Acta, 2003, 406, 191 – 198. 4. Vecchio, S.; J. Therm. Anal.
Cal., 2007, 87, 79 – 83. 5. Lyman, W.; Environmental Exposure
from Chemicals, vol 1, Chapter 2, CRC Press, Boca Raton,
1985. 6. Vecchio, S.; Catalani, A.; Rossi, V.; Tomassetti, M.;
Thermochim. Acta, 2004, 420, 99 – 104. 7. Yaws, C. L.;
Handbook of vapor pressure, vol 3, Gulf Publishing Company,
Houston (TX) , 10th ed., 1994. 8. Chickos, J. S.; Hosseini, S.;
Hesse, D. G.; Liebman, J. F.; Struct. Chem., 1993, 331, 261 –
269.
P 1.39
Antimicrobial peptides chelating lanthanide
ions: the case of Trichogin GAIV analogs and
Terbium(III)
Mariano Venanzi,a Emanuela Gatto,a Lorenzo Stella,a
Gianfranco Bocchinfuso,a Antonio Palleschi,a Fernando
Formaggiob and Claudio Toniolob
a
Department of Chemical Sciences and Technologies,
University of Roma Tor Vergata, 00133 Rome, Italy,
[email protected]
70
b
characterization of their physico-chemical behavior
(aggregation in water and in the membrane, membranewater partition, position and orientation in the bilayer,
translocation across the membrane). These studies
allowed us to discriminate between different models for
the mechanism of action, showed that simple
modifications in the peptide sequence (e.g. lipidation)
perturb peptide partition and aggregation equilibria, and
helped us to explain why these changes can lead either to
an increase or to a reduction in the overall membrane
perturbing activity, depending on the specific case. In
addition, experiments on giant unilamellar vesicles
(GUVs) provided a direct view of the peptide-induced
leakage process. Finally, molecular dynamics simulations
starting from a random mixture of water, lipids and
peptide, showed in atomic detail the process of bilayer
formation, and provided a prediction of the peptide
location inside the bilayer in perfect agreement with
experimental data. Data on trichogin GA IV are reported
here, as a typical test case.
Department of Chemistry, University of Padua, 35131
Padua, Italy
Lanthanide chelates are actively explored for potential
applications in medical diagnostics, bioimaging and
bioanalytical assays. One major problem to be faced for
the utilization of lanthanides is their insertion and
vehicolation through the membrane phase. Specifically
designed oligopeptides, due to their ability to fold into
specific structures, to bind membranes or proteins, and to
transport ions and small organic molecules, represent
promising novel smart materials to be investigated.
We report on the ion binding properties of two
fluorescent analogs of trichogin GA IV, a natural peptide
showing interesting antimicrobial activity.
Primary
structures (and acronyms) of the peptides investigated
are:
Fmoc-Aib-Gly-Leu-Aib-Gly-Gly-Leu-Aib-Gly-Ile-LeuOMe (F0)
nOct-Aib-Gly-Leu-Aib-Gly-Gly-Leu-Aib-GlyDab(Fmc)-Leu-OMe (F10)
where Aib is α-aminoisobutyric acid, Fmoc is fluoren-9ylmethyloxycarbonyl
and
Fmc
fluoren-9ylmethylcarbonyl.
1. Con il contributo del Ministero degli Affari Esteri.
CD titration experiments with Tb(III) revealed that, upon
ion binding, both F0 and F10 undergo a conformational
transition, forcing the peptide chain to attain folded, nonhelical structures. Upon ion binding the fluorescence of
Tb(III) markedly increased, due to an energy transfer
process from the fluorene excited state to Tb(III). The
occurrence of a Förster energy transfer (FRET)
mechanism is made possible by the spectral overlap
between the emission spectrum of the donor molecule
(fluorene) and the absorption of the acceptor species
[Tb(III)]. The excitation spectrum carried out at the
acceptor emission wavelength confirmed the transfer of
excitation energy in the Fluorene→Tb(III) direction.
From FRET experiments we found that the donoracceptor distance in the F0-Tb(III) complex is 12Å, while
in the F10-Tb(III) it is 5.8Å. These results suggest that
the ion binding site is close to the C-terminus of the
peptide chain. Molecular mechanics calculations are
currently underway, to obtain structural information on
the ion-peptide complex.
P 1.41
A novel method for detection of Se-Met
inclusion into protein crystals via Raman
microscopy
Alessandro Vergara,a, b,c Antonello Merlino,a Elio
Pizzo,d Giuseppe D’Alessio,d and Lelio Mazzarellaa,b,c
a
Dipartimento di Chimica, Università degli Studi di
Napoli “Federico II”, Complesso Monte S. Angelo, Via
Cinthia, I-80126. Napoli, Italia, [email protected]
b
Istituto di Biostrutture e Bioimmagini, CNR, via
Mezzocannone 6, I-80134 Napoli,
c
Consorzio Bioteknet, University of Naples “Federico
II”, 80126 Naples, Italy.
d
Dipartimento di Biologia strutturale e funzionale,,
Università degli Studi di Napoli “Federico II”,
Complesso Monte S. Angelo, Via Cinthia, I-80126.
Napoli, Italia
.
Multiwavelength anomalous dispersion (MAD) is the
most widespread approach in structural biology to
determine the crystal structure of a novel protein. Mass
spectrometry is currently used to evaluate the Se-Met
content in solution, but a routine method to check the SeMet inclusion and storage in the crystal state is not yet
available. Raman microscopy is having increasing
application into molecular biology, ranging from studies
on ligand binding [1] and secondary structure analysis
[2]. Here we present a novel tried-and tested
methodological development to conduct, via Raman
microscopy, analysis on Se-Met labelled protein crystals
to be used for MAD crystallography. The method is
described, and is supported by validation and application
to two novel proteins (a βγ-crystallin-like protein and a
DNA-binding protein). Markers of the Se-Met residues
are in the range from 570-600 cm-1, where proteins
usually do not show any Raman band.
P 1.40
Effect of aggregation and membrane-water
partition on peptide antimicrobial activity: a
lesson learned from spectroscopic studies.
L. Stellaa, C. Mazzucaa, G. Bocchinfusoa, F. Formaggiob,
E. Gattoa, K. S. Hahmc, A. Palleschia, B. Pispisaa, C.
Toniolob, M. Venanzia
a
Dipartimento di Scienze e Tecnologie Chimiche,
Università di Roma Tor Vergata, 00133 Roma, Italy.
[email protected]
b
Dipartimento di Chimica, Università di Padova, 35131
Padova, Italy.
c
Research Center for Proteineous Materials, 501-759
Gwangju, Korea.
Notwithstanding the great potential of antimicrobial
peptides as new antibiotic agents, the rational design of
new analogues with improved activity, selectivity and
bioavailability properties remains challenging. In a series
of studies on different antibiotic peptides (trichogin GA
IV, alamethicin, PMAP-23), we combined several
spectroscopic techniques to obtain a detailed quantitative
1.
2.
71
P. R.Carey, J. Dong, Biochemistry 2004, 43, 88858893.
P. R. Carey, Ann. Rev. Phys. Chem. 2006, 57, 527554.
photodegrade methylene blue. Thus surface area of
the nanovoid structured TiO2 is about one order of
magnitude lower that that of the P25 commercial
TiO2 photocatalyst, but its ability to degrade
methylene blue is comparable. This implies that the
surface specific degradation efficiency of this new
material is about ten times higher than that of the
P25.
P 1.42
Nanovoid-structured TiO2 encapsulating (I2)n
molecules: a way to tune the photoactivity in the
visible region
A. Zecchina, G. Ricchiardi, S. Usseglio, A. Damin, D.
Scarano, C. Lamberti, S. Bordiga
a
Centro di Eccellenza NIS, Dipartimento di di Chimica
IFM, Via Giuria 7, 10125 Torino,
[email protected]
Among all the semiconductors used in
photocatalysis, TiO2 is essentially the best material
for environmental remediation. The only drawback
of TiO2, is that its band gap lies in the near UV of
the electromagnetic spectrum: 3.2 eV (285 nm) and
3.0 eV (410 nm) for anatase and rutile respectively.
As a consequence, only UV light is able to create
electron-hole pairs and to initiate photocatalytic
process. As UV light constitutes only 5% of the
solar spectrum , 95% of the solar photons are
useless for TiO2 photocatalysts. It is therefore
evident that any modification of the TiO2-based
photocatalysts resulting in a lowering of its band
gap, or in the introduction of stable optical
sensitizes, will represent a breakthrough in the
field.
A new strategy to synthesize a TiO2 characterized
by the presence of internal nanovoids is presented.
It consists in the hydrolysis at room temperature of
pure Ti(OC3H7)4 in air (30-40% humidity),
according to Equation: Ti(OC3H7)4 + 2H2O → TiO2
+ 4 C3H7OH. After 36 hours the white powder
obtained was dried at 373 K in an oven and then
calcined in air at 773 K for 6 hours.
P 1.43
MeCAL-2:
combustion
New
catalysts
for
methane
G. A. V. Martins a, G. Berlier a, M. Straussc, S.
Colucciaa, L. Marcheseb, Heloise O. Pastorec, A. Scarpad,
R. Pironed
a
Dipartimento di Chimica IFM, Università di Torino,
Turin
I-10125
Italy,
[email protected],
b
Dipartimento di Scienze e Tecnologie Avanzate,
Università del Piemonte Orientale, Alessandria I-15100,
Italy cInstituto de Química, Universidade Estadual de
Campinas, Campinas-SP, Brasil. dIstituto di Ricerche
sulla Combustione IRC-CNR, Napol, Italia. e-mail:
[email protected].
The search for clean energy sources is the object of study
of many research groups. Catalytic combustion is an
environmentally friend alternative for heat and power
generation using fossil fuels, since it is possible to obtain
very efficient burning at concentrations below the
flammability limits and at lower temperatures than in the
conventional flame combustion, without undesired byproducts such as UHC (unburned hydrocarbons), CO and
NOx [1]. The present work describes the characterization
of a new kind of microporous materials containing
transition metal ions, the MeCAL-2, active for
hydrocarbon combustion.
[1] M. Zwinkels, S.G. Jaras, P.G. Menon, in: A.
Cybulski, J. Moulijn (Eds.), Structured Catalysts and
Reactors, Marcel Dekker, New York, 998, p. 149.
P 1.44
Pt-Ba/Al2O3 LNT catalysts: TRM and FT-IR
analysis of the reduction of stored NOx in
different model atmospheres
F. Frola1, F. Prinetto1, G. Ghiotti1, I. Nova2, L. Lietti2, P.
Forzatti2
Fig. 1 pure and I2-doped TiO2 samples and their UV-Vis
Diffuse Reflectance spectra.
1
Dipartimento di Chimica IFM, and NIS Centre of
Excellence, Università di Torino, Via P. Giuria 7, 10125
Torino. [email protected]
2
Dipartimento di Chimica, Materiali e Ingegneria
Chimica “Giulio Natta”, Centro NEMAS—Nano
Engineered Materials and Surfaces, Politecnico di
Milano, Piazza Leonardo da Vinci 32, 20133 Milano.
The walls of the internal cavities are populated by
adsorbed molecular species derived form the partial
combustion of isopropoxide groups. Addition of
iodine as dye molecule in the synthesis procedure
results in a new nanovoid structured titanium oxide
characterized by (I2)n adducts encapsulated inside
the cavities that in this way are protected from
degradtion. The resulting material is able to absorb
visible photons of the solar light and to
Introduction
“Lean NOx Trap” (LNT) systems, constituted by a NOxstorage component (alkaline or earth-alkaline metal
oxide) and by a noble metal (Pt) which operates the NOx
72
reduction. Moreover, weak bands at 2242 and 2164 cm-1
appeared starting from 150°C, reasonnably due to the
presence of surface cyanate and/or isocyanates. As in the
case of CO2, FT-IR experiments performed with H2/H2O
mixture were in agreement with TRM data, confirming a
benefical effect of water on the reduction of stored
nitrates, i.e lowering the temperature at which the
reduction starts. Since TRM data show that NH3 is the
main product at temperature up to 150 °C, dedicated FTIR experiments were involving reduction of the stored
NOx in pure H2 at 150°C followed by cooling the
catalyst in the reaction mixture down to RT in order to
detect the adsorbed NH3 possibly formed. When the
sample is cooled to RT, no traces of adsorbed NH3, but
hydroxyls, small amounts of coordinated water and of
nitrites were detected. With the aim to understand the
origin of the nitrite formation a new series of FT-IR
analysis was performed: NOx species were first stored at
350°C at different coverage, sample was cooled down to
RT and increasing amount of H2O or D2O were adsorbed
up to the vapor saturated pressure. Nitrites are always
observed to form in increasing amounts on increasing the
H2O or D2O coverage, showing that their formation is a
peculiar results of the interaction of water at RT with a
surface not satured with nitrates. Both TRM and FT-IR
data are consistent with a reaction pathway in which H2
is dissociated on Pt sites, followed by spillover of the
atomic H towards the stored nitrates leading to their
destabilization/decomposition and to their reduction. CO2
inhibits the reaction due to CO adsorption on Pt whereas
water would favour the process by enhancing the H
spillover. In this light, the selectivity of the process (i.e.
NH3 vs. N2 formation) might be governed by the NOx/H
ratio, i.e on the relative abundance of NOx surface species
and of the split H. Besides, the participation of NH3 byproduct in the reduction of stored NOx cannot be
excluded.
reduction, represent the most promising solution to
satisfy the demand for new catalytic systems efficient in
reducing NOx emissions by engines working under “lean”
conditions [1]. Although used at commercial scale in
Japan, a common agreement on the mechanistic aspects
of the storage of NOx species and of their reduction is
still lacking [1]. Our previous studies showed that the
NOx storage process occurs through two parallel ways,
the “nitrite” and “nitrate" routes (the former occurring
only when stored NOx originated from NO/O2 mixtures,
the latter both in the cases of storage of NO/O2 mixtures
or NO2) [2, 3]; in this study we used again FT-IR
spectroscopy and the transient response method (TRM)
as complementary techniques with the aim of providing
new insights on the reduction by hydrogen of stored
nitrates over Pt-Ba/Al2O3.
Experimental
Reduction of NOx stored on Pt-Ba/Al2O3 model catalyst
(Pt=1% w/w, Ba=16% w/w) at 350°C by imposing a
rectangular step feed of NO (1000 ppm) in flowing He +
3% v/v O2 (TRM experiments) or admitting NO/O2 1:4
mixture (FTIR experiments, pNO=4mbar) was studied at
different temperatures, in the range 100-350°C, by
imposing a stepwise change in the H2 concentration
(2000 ppm) (TRM) or admitting pure H2 pH2=5 mbar
(FTIR) The effect of the presence of CO2 and/or water
during the reduction phase was also analysed.
Results and discussion
TRM regeneration procedures following NOx adsorption
at 350°C were performed at different temperatures in the
range 100-350°C. At temperatures below 150°C the NOx
reduction was very slow and delayed with respect to
hydrogen admission, and NH3 was the main reaction
product. In the range of temperatures 150-300°C the
reduction process was very fast, but higher ammonia
formation and a not complete removal of the stored NOx
was observed. At 350°C, H2 was immediately consumed
with an immediate selective formation of N2; small
amounts of NO were also detected in the gas phase at the
beginning of the reduction process. Then, when hydrogen
appeared into the gas phase, the concentration of nitrogen
decreased and after H2 breakthrough, evolution of
ammonia was observed. Similar experiments were also
performed in the presence of water or CO2: data showed
that water favoured the rate of NOx reduction, whereas
CO2 had an adverse effect. No significant effects on the
nitrogen selectivity were observed. A parallell FT- IR
study was carried out during which the evolution of
stored NOx with the temperature in the different
atmospheres was analyzed. In the case of pure H2 the
results were in line with the TRM experiments: nitrate
reduction started at 150 °C and was completed at 250°C.
The presence of CO2 inhibits the NOx reduction, as also
pointed out by TRM data. No reaction intermediates or
reaction products are detected by IR spectroscopy using
pure H2. At variance, using the H2/CO2 mixture, starting
from 100°C weak absorptions between 2070 and 2020
cm-1 were detected, due to CO linearly adsorbed on Ptδ+
or Pt0. This shows that the reversed water shift reaction
takes place and CO adsorbed on Pt inhibits the NOx
Conclusions
The reduction of the stored NOx over a model PtBa/Al2O3 catalysts under different atmospheres at
different temperatures was investigated by TRM and FTIR spectroscopy, showing that the NOx reduction
pathway and the selectivity of process strongly depend on
operating conditions. Further TRM and FT-IR analyses
are currently in progress which analyse ammonia
formation and its possible involvement as intermediate
species in the mechanism governing the reduction of NOx
adsorbed specie by H2.
References
[1] Epling W.S, Campbell L.E., Yezerets A., Currier N.W.,.Park
II J.E, Catal.Reviews, 46(2) (2004) 163
[2] Nova I., Castoldi L., Prinetto F., Ghiotti G., Lietti L.,
Tronconi E.,.Forzatti P, J.Catal, 222/2 (2004) 377
[3] Nova I., Castoldi L., Lietti L., Tronconi E.,.Forzatti P,
J.Catal, 239 (2006) 244
73
SEZIONE
SPETTROSCOPIA E FOTOCHIMICA
74
stable under long term irradiation with UV-Vis light. The
described properties render the prepared NCs good
candidates for animal imaging and for photovoltaic
devices applications.
P 2.1
Small, Infrared, Luminescent Type II
Semiconductor Nanocrystals for Animal
Imaging
1. Kim, S.; Fisher, B.; Eisler, H. J.; Bawendi M.; J. Am. Chem.
Soc. 2003, 125, 11466-11467. 2. Sevick-Muraca, E. M.;
Houston, J. P.; Gurfinkel M.; Curr. Opin. Chem. Biol. 2002, 6,
642-650. 3. Kim, S.; Lim, Y. T.; Soltesz, E. G.; Grand, A. M. D.;
Lee, J.; Nakayama, A.; Parker, J. A.; Mihaljevic, T.; Laurence,
R. G.; Dor, D. M.; Cohn, L. H.; Bawendi, M. G.; Frangioni, J. V.
Nat. Biotechnol. 2004, 22, 93-97.
Matteo Amelia, Loredana Latterini, Gian Gaetano Aloisi
and Fausto Elisei
Dipartimento di Chimica and Centro d’ Eccellenza
Materiali
Innovativi
Nanostrutturati
(CEMIN),
Università degli Studi di Perugia, Via Elce di Sotto 8,
06123 Perugia, [email protected]
Recently introduced Type II quantum dots1 possess both
the valence and the conduction band with higher, or
lower, energy than the core ones. As a result, one carrier
is mostly confined to the core, while the other is mostly
confined to the shell. Consequently two different classes
of Type II QDs can be assembled, one class where the
shell presents both the valence and the conduction band
at a lower energy with respect to the core, which has
holes mostly confined in the core and electrons mostly
confined in the shell. Despite, the second class possesses
a shell with both the valence and the conduction band at
higher energy compared to those of the core, bringing to
confine mostly the electrons in the core and the holes in
the shell.
Type II quantum dots provide access to wavelength not
previously available with a single material, especially in
the spectral NIR region (700-1000 nm). This is highly
desirable for in vivo imaging because of the enhanced
contrast resulting from the separation of the nanocrystal
photoluminescence
from
the
autofluorescence
background and of the increased penetration of both
excitation and emission light through tissues2. The
applicability of NIR type II quantum dots to biomedical
in vivo imaging has been already proved with the
employment of CdTe/CdSe for limph-node mapping in
both mice and pigs animal models3. Moreover, the spatial
charge separation delays the hole-electron recombination
bringing to an extremely long fluorescence lifetime. One
of the applicative field that can be improved by the
introduction of Type II heterostructures is the building up
of photovoltaic devices. In fact, in Type I systems
photogenerated electrons and holes are concentrated in
the core region and their effective separation requires
additional excitation into the matrix material, which may
suppress the effectiveness of photovoltaic devices, but in
Type II systems such barriers are absent, at least for one
type of carriers.
In the present work, the CdTe shell deposition on a CdSe
core template building a “reverse” Type II CdSe/CdTe
heterostructure is reported. The particles synthesized are
highly monodispersed and show new optical properties.
The almost featureless absorption spectrum possesses a
NIR band (detected by PLE spectroscopy) allowing
excitation where the light is more penetrative through the
tissues. The emission spectrum has been proved to
emerge from the two materials interband and to change in
the NIR region with the number of shell layers deposited
on the template core structure. The system has a high
fluorescence quantum yield (up to 20%) comparable with
the Type I core/shell QDs and a long lifetime (about 70
ns) that ensures the obtained spatial charge separation.
The employment of Successive Ion Layer Adsorption and
Reaction (SILAR) has been revealed to be crucial in
order to achieve an improvement in the radiative process
and in the quality and the homogeneity of the particles.
The Type II nanocrystals can be further build up, with
minor modifications to the original synthetic scheme, and
render water-soluble and bio-compatible. They also result
P 2.2
Doped Nanocrystals: Coupling Optical and
Magnetic Properties
Matteo Amelia, Loredana Latterini, Gian Gaetano Aloisi
and Fausto Elisei
Dipartimento di Chimica and Centro d’ Eccellenza per i
Materiali
Innovativi
Nanostrutturati
(CEMIN),
Università degli Studi di Perugia, Via Elce di Sotto 8,
06123 Perugia, [email protected]
Cadmium based semiconductor nanocrystals have been
intensively studied in the past three decades due to their
enormous advantages versus organic dyes, such as broad
excitation profile and by a narrow (FWHM = 25-35 nm)
and tunable, accordingly to size, photoluminescence
spectrum1. However, recently, many concerns have been
moved against those systems for the intrinsic toxicity of
Cd2+ that can compromise the future of cadmium
chalcogenide nanocrystals in biological applications,
especially in vivo (animal models and human body).
Within this picture it has been appeared necessary move
toward the synthesis and characterization of greener
systems.
Manganese doped nanocrystals seems to be the most
attractive systems because of their Stokes’s shift of about
150 nm and of their red and strong quantum efficiency2.
In the present Chapter, a decoupling nucleation strategy
for doped nanocrystals synthesis is reported3. The main
innovative aspect, with respect to the already described
methods, is the possibility to get the core/shell
nanosystem in a easy way by using only one shell
precursor and one shell deposition temperature.
The synthesized manganese-doped nanocrystals show a
strong photoluminescence intensity (quantum yield of
about 30%) centred at 590 nm. The PL peak is slightly
affected by size effects opening new possibilities to the
employment of nanocrystals in bio-imaging. For instance,
it is possible to keep the same emission profile changing
the hosting materials and the sizes. Moreover,
nanoparticles with same size and hosting materials but
with different photoluminescence peaks, might be
prepared just exchanging the impurity atoms (e.g. Cu for
green PL and Eu for NIR PL) in the same host.
A secondary shell was deposited on the nanocrystals to
enhance the persistency of the emission intensity,
generally related to the ability of manganese atoms to
diffuse at the nanocrystal surface during the purification,
irradiation and ageing processes. The latest synthetic step
brought to nanocrystals with robust and stable emission
properties.
MnSe/ZnSe/ZnS NCa posses an absorption spectrum
close to the bare ZnSe NCs (which is the absorbing
species) and a PL spectrum linked to the atomic emission
75
between d states belonging to the manganese doping
atoms. They have an high quantum yield and a short
lifetime (4 ns). The samples are fairly monodispersed
being mainly constituted by one size, as proved by TEM
imagines and analysis. Their dimensions may widely
range from 2 to 10 nm.
The bioactivation of the ZnS, realized via peptidecoating4, affected mainly the QY that drops to 3-4%. That
low value was proved to be to due to an incomplete
surface coverage, so that it can be raised up by a
secondary water stabilizer (such as thioglycerol).
Magnetic properties of the doped nanocrystals arising
from the manganese have also been demonstrated by
Superconducting Quantum Interferometer Devices
SQUID measurements. The coupling of optical and
magnetic properties in one marker might be tremendously
advantageous in biomedicine due to the double imaging
mode.
measured their decay kinetics in air and anoxic
conditions. The effects of photodegradation of paper has
also been investigated using a magnetic resonance
technique such as NMR relaxometry, using a single-sided
low-field NMR instrument. Our aim is to develop a fast
and non-invasive method for the evaluation of the degree
of cellulose depolimerization and the water content in
paper by means of the analysis of 1H nuclear relaxation
times [1].
A further interesting research regards the assessment of
the quarry of ancient white marbles. We have studied by
EPR spectroscopy the Mn(II) spectra in a series of white
marble samples coming from a local archaeological
excavation site of roman age (Montegrotto; Padova) and
from Museo degli Eremitani, Padova. Mn(II) EPR spectra
allow the identification of the provenance of white
marble [2], thanks to a database collecting the Mn(II)
EPR parameters of most of the ancient quarries.
1. Michalet, X.; Pinaud, F. F.; Bentolila, L. A.; Tsay, J. M.;
Doose, S.; Li, J. J.; Sundaresan, G.; Wu, A. M.; Gambhir S. S.;
Weiss S.; Science 2005, 307, 538-544. 2. Bhargava, R. N.;
Gallagher, D.; Hong X.; Nurmikko A.; Phys. Rev. Lett. 1994,
72, 416-419. 3. Pradhan, N. ; Goorskey, D.; Thessing J.; Peng
X.; J. Am. Chem. Soc. 2005, 127, 17586-17587.4. Pinaud, F.;
King, D.; Moore H. P.; Weiss S.; J. Am. Chem. Soc. 2004, 126,
6115–6123.
1. Blumich, B.; Anferova, S.; Sharma, S.; Segre, A.L.; Federici,
C.; J. Mag. Reson. 2003, 161(2), 204 – 209. 2. Attanasio,
D.;Ancient White Marbles-Analysis and Identification by
Paramagnetic Resonance Spectroscopy- Ed. <<L’Erma> 2003
P 2.4
The triplet of DCM observed for the first time:
a TR-EPR study of the dye inclusion in a KH
Phthalate single crystal.
P 2.3
Magnetic Resonance investigations on Cultural
Heritage materials.
Marina
Brustolon#, Roberto Zanré#, Antonio
Barbon#, Kristin L. Wustholz§, Bart Kahr§
#Department of Chemical Sciences, Via Marzolo 1,
35131-I, Padova, (Italy)
§ Department of Chemistry, University of Washington,
Box 351700, Seattle, WA 98195-1700 (USA)
Alfonso Zoleoa, Marco Ruzzia, Lorenzo Francoa, Daria
Confortina, Marina Brustolona
a
Department of Chemical Sciences, University of Padova,
via
Marzolo
1,
35131
Padova,
[email protected]
N
Modern spectroscopic techniques for the investigations of
art works and archeaeological materials can give a
fundamental contribution for a deeper knowledge of the
techniques of production, provenance, conservation status
and degradative processes of a broad range of materials
and objects.
We applied magnetic resonance methods, mainly
Electron Spin Resonance spectroscopy and Nuclear
Magnetic relaxation methods to the analysis of several
materials such as ancient paper and marbles, with the aim
to develop a reliable method for the provenance and the
evaluation of the conservation status.
Several samples of paper dating from the XV to the XX
century have been investigated using CW-EPR
spectroscopy.
Ancient
paper
specimens
were
characterized by apparent signals from radicals, Mn(II),
Cu(II) and Fe(III). The relative intensity among the
signals was found dependent on the samples, with
interesting correlations, e.g., strong Cu(II) signals are
detected in deteriorated samples, quite independently of
the age of the sample. Furthermore, a comparison among
several paper samples from ancient books showed that
EPR Mn(II) signal could possibly be used as a marker of
the paper origin. We also investigated the photoinduced
generation of radicals in ancient paper composed of pure
cellulose and in modern paper, which is composed also of
lignin and other components. By conventional and pulsed
EPR spectroscopy we identified several UV-induced
radicals in the cellulose and in the lignin components, and
N
O
CH3
N (CH3)2
DCM
Colourless crystals of simple salts grown from solution
in presence of a dye can be stained by molecules many
times larger than those of the host. They are called Dyes
Inclusion Crystals (DIC) [1] . Time Resolved EPR is a
convenient technique to study some of their singular
properties, as e.g. the orientations of the included dyes,
breaking often the bulk symmetry of the host [2]. 4dicyanomethylene-2-methyl-6-(p(dimethylamino)styryl)-4H-pyran (DCM) is a laser dye
with a push-pull structure. It has many interesting
properties arising from the charge transfer that occurs in
the excited state. Its photophysical behaviour has been
investigated by numerous authors, with different
spectroscopies. Its triplet state had never been observed
till the present study. We have investigated DCM in a
single crystal of KAP (Potassium Acid Phthalate) by
Time-Resolved EPR. In this rigid matrix we have been
able to observe for the first time the photoexcited triplet
of DCM. Its ZFS parameters have been compared with
computations sensitive to the conformation of the excited
state.
Moreover, we have obtained interesting results on the
orientations of the dye giving rise to the triplet state,
76
which is included only in {11-1} growth sector. We have
isolated two sub-volumes from this sector, cutting the
fragment along the c axis. We have found that the DCM
molecules giving the triplet spectrum are present in each
sub-sector in an unique orientation, and with slightly
different ZFS parameters. The two orientations are not
symmetry related, despite the fact that the two subsectors are mirror images one of the other. The breaking
of the crystal symmetry may be explained as a
consequence of intrasectoral zoning via the vicinal faces
of growth hillocks. Intrasectoral zoning is here observed
for the first time by EPR.
P 2.6
Spectral studies of Nicotinamide and Zinc
phthalocyanine complexes
R. Del Solea, M. R. Lazzoia, A. De Lucaa, G. Vasapolloa
Dipartimento di Ingegneria dell’Innovazione, Universita’
Degli Studi di Lecce, via per Monteroni, km1, 73100,
Lecce, [email protected].
Phthlocyanines (Pcs) and metallo phthalocyanines
(MPcs) are nowdays considered very attractive materials
for their technological applications such as gas sensors,
solar cells, homogeneous and/or heterogeneous catalysts,
photodynamic therapy and so on [1]. It is well known that
the properties of these compounds depend strongly on the
nature of the metal, substituents and coordinated ligands
[2]. Generally, the presence of alkyl or aryl groups as
peripheral substituents or coordinated ligands in the
molecules can improve the solubility but also can
influence the physical and photo-physical properties.
Nicotinamide (NAM) is an important molecule widely
diffused in nature as a form of vitamin B3. NAM is also
part of nicotinamide adenine dinucleotide (NAD) and
nicotinamide adenine dinucleotide phosphate (NADP)
coenzymes and consequently it is involved in various
redox processes into the human body [3].
For long time we have been interested in the synthesis of
new phthalocyanines and in the study of their
coordinating properties with particular molecules [4]. So
that, continuing our research in this area, we report here
spectral studies and job plot analyses which provide
evidence of complexes formation of zinc phthalocyanines
and zinc naphthalocyanines complexes with nicotinamide
(NAM) and with its isomers isonicotinamide (iNAM) and
picolinamide (PAM). To validate complexes formation
some of them have been also isolated and fully
characterized by FT IR and NMR spectroscopic
techniques.
1. B. Kahr, R. W. Gurney, Chem. Rev. 2001, 101, 893.
2. A. Barbon, M. Bellinazzi, J. B. Benedict, M.
Brustolon, S. D. Fleming, S.-H. Jang, B. Kahr, A. L.
Rohl, , Angew. Chem. Int. Ed. Engl., 2004, 43, 52785286; M. Bellinazzi, A. Barbon, B. Kahr, J. B. Benedict,
M. Brustolon , 2006, PCCP, 8, 379-385.
P 2.5
Laser Ablation-Inductively Coupled Plasma
Mass Spectrometry for the Determination of
Heavy Metals in Airborne Pariculate Matter
(Pm10)
Ameriga Fanigliulo, Giuseppe E. De Benedetto
Laboratorio di Analisi Chimiche per i Beni Culturali e
per l'Ambiente, Dipartimento dei Beni delle Arti e della
Storia, Università del Salento, viale San Nicola, 73100
Lecce. e-mail: [email protected]
The coupling of Laser Ablation (LA) with Inductively
Coupled Plasma Mass Spectrometry is applied for the
qualitative and quantitative determination of heavy
metals suspended in airborne inhalable particulate matter,
sampled with an impactor high volume air sampler on
quartz fiber filters. The easy, rapid, non-destructive
method is proposed as a rapid screening procedure for
this peculiar environmental specimen. The un-necessity
of a preparative/extracting or diluting step and the
absence of the stressing conditions generally included in
that step (temperature, microwave power, strong acids...)
dramatically reduces the probability of interferences or
understimating errors [1, 2]. On the other hand, a major
statistical study is needed in planning instrumental
conditions and data collecting, in order to ensure valuable
and reproducible numerical data. We propose a crosscalibration procedure which uses the results obtained on
some of the specimens of the sample batch, analysed after
acidic digestion and interpolated on a acqueos standard
solution calibration curve, as reference points for the
direct quantification of the remaining samples, analysed
under laser ablation. Real samples from a traffic city site
and a rural site, taken as blank, were analysed and
compared with acidic digestion analysis. The method was
proved to be affordable, reliable and rapid to set.
O
NH2
O
γ
β
NH2
N
N
isonicotinamide
(iNAM)
nicotinamide
(NAM)
α
N
O
NH2
picolinamide
(PAM)
N
N
N
N
1
N
N
Zn
N
N
N
N
N
N
Zn
N
N
N
N
2
1. a) McKeown, N. B.; Phthalocyanine Materials: Synthesis,
Structure and Function, Cambridge University Press:
Cambridge, 1998; b) De La Torre, G.; Claessens, C. G.; Torres,
T.; Eur. J. Org. Chem., 2000, 2821-2830.
2. a) Barthel, M.; Dini, D.; Vagin, S.; Hanack, M.; Eur. J. Org.
Chem., 2002, 3756; b) Tomachynski, L. A.; Chernii, V.Y.;
Volkov, S. V.; J. Porphyrins Phthalocyanines, 2001, 5, 731.
3. Williams, A.; Ramsden, D.; Parkinsonism Relat. Disorders,
2005, 11, 413.
4. Del Sole, R.; De Luca, A.; Mele, G.; Vasapollo, G.; J.
Porphyrins and Phthalocyanines, 2005, 9 (7), 519.
Wang, C.-F.; Chin, C.-J.; Luo, S.-K.; Men, L.-C; Anal. Chim.
Acta, 1999, 389, 257-266. 2. Rauch, S.; Lu, M.; Morrison, G.
M.; Environ. Sci. Technol. 2001, 35, 595-599
77
1. Gallina, M. E.; Sassi, P.; Paolantoni, M.; Morresi, A.;
Cataliotti, R. S.; J. Phys. Chem. B, 2006, 110, 8856 – 8864. 2.
Fioretto, D.; Comez, L.; Gallina, M. A.; Morresi, A.; Calmieri,
L.; Paolantoni, M.; Sassi, P.; Scarponi, F.; Chem. Phys. Lett. in
press. 3. Morresi, A.; Sassi, P.; Paolantoni, M.; Gallina, M. E.;
Fioretto, D.; Comez, L. in preparation.
P 2.7
Studio degli ioni Mg2+ e Ca2+ in metanolo liquido
attraverso dinamica molecolare ab initio CarParrinello
Cristian Farallia, Marco Pagliai, Gianni Cardinia,b e
Vincenzo Schettinoa,b
a
Laboratorio di Spettroscopia Molecolare, Dipartimento
di Chimica, Università di Firenze, via della Lastruccia 3,
50019,
Sesto
F.no,
Firenze,
Italia,
[email protected]
b
European Laboratory for Nonlinear Spectroscopy
(LENS), via Nello Carrara 1, 50019, Sesto. Fno, Firenze,
Italia
P 2.9
Competitive photoisomerization pathways of
1,2-diarylethenes and related compounds
Le proprietà di solvatazione degli ioni Mg2+ e Ca2+ in
soluzione di metanolo completamente deuterato sono
state indagate attraverso simulazioni di dinamica
molecolare ab initio Car-Parrinello al fine di
comprendere meglio gli effetti di polarizzazione che
insorgono per la presenza dello ione. E’ stato analizzato
l'effetto
delle dimensioni del campione sul
comportamento delle molecole della prima sfera di
solvatazione senza trovare una particolare influenza sulle
proprietà strutturali. Calcoli di trasferimento di carica e di
momento di dipolo sono stati esaminati per descrivere
dettagliatamente il
ruolo della riorganizzazione
elettronica e comprendere l'influenza sulla stabilità della
prima sfera di solvatazione. I dati ottenuti sono stati
confrontati con i risultati delle precedenti analisi per i
metalli alcalini (Li+, Na+ e K+).
G. Bartocci, S. Ciorba, G.Ginocchietti, U. Mazzucato and
A. Spalletti
Dipartimento di Chimica and Centro di Eccellenza
Materiali
Innovativi
Nanostrutturati
(CEMIN),
Università di Perugia, 06123 Perugia, Italy;
[email protected] (Spalletti, A.)
The interest of our laboratory in the internal
rotation around the double bond in 1,2-diarylethenes and
related compounds has been recently focused on the
geometric photoisomerization occurring on a unique
potential energy surface by an adiabatic mechanism, i.e.
giving rise to an electronically excited photoproduct. The
main factors responsible for this behaviour are the nature
and energy of the lowest excited states of singlet (S1) or
triplet (T1) multiplicity of these flexible molecules and
the relative position of the energy levels of the excited
twisted configuration (1,3perp*) with respect to the quasiplanar (1,3trans* or 1,3cis*) excited forms. In fact, the
common diabatic mechanism of the geometric (cis/trans)
photoisomerization of 1,2-diarylethenes, implying
rotation to the 1,3perp* configuration, followed by internal
conversion to the twisted ground state (1perp) and
equipartitioning to the ground trans and cis forms, can
compete with (or to be completely replaced by) the
adiabatic process from one to the other quasi-planar
excited states when the twisted form is at a maximum in
the potential energy surface describing the isomerization
process. This generally (not always) occurs in non-polar
solvents when a one-way cis → trans photoisomerization
is operative.
The cross-road between the competitive
pathways would depend on the energy of the twisted
geometry: when 1,3perp* is at a flat position or shallow
minimum, some molecules undergo S1 → S0 internal
conversion there, but others may continue on the same
surface towards the excited planar isomer. On the other
hand, when the 1,3perp* is at higher energy with respect
to at least one of the planar geometries, particularly
1,3
trans*, the photoisomerization may really occur on a
unique potential energy surface, without crossing (or
avoided crossing) with the descendent curve of an upper
excited state of the same multiplicity.
The present contribution will describe some
typical examples of adiabatic photoisomerization recently
evidenced by fluorimetric, flash photolytic and
photochemical techniques and confirmed by theoretical
calculations. A speculative hypothesis that the mixed
mechanism may involve two distinct pathways since the
beginning of the twisting process from the starting
(planar) geometry is under investigation.
Internal rotation around the quasi-single bonds
between the aryl groups and the ethenic carbons is also
investigated since it can play a role in the geometric
P 2.8
Low-frequency Raman scattering from aqueous
solutions of carbohydrates
S. Perticaroli, P. Sassi, A. Morresi, M. Paolantoni
Dipartimento di Chimica, Università di Perugia, Via
Elce di Sotto, 8, I-06123 Perugia, Italy
Understanding the dynamics of water molecules in
aqueous solutions of complex biological systems is a
subject of considerable interest, due to the fundamental
role played by the water in determining the properties of
these systems.
Raman and depolarized Rayleigh scattering (DRS)
techniques are powerful probes in the study of structural
and dynamical properties of carbohydrates aqueous
solutions.1,2 In our laboratory, with regard to glucose and
trehalose, we have shown that the contribution of the
sugar dynamics is well separated from that of water
molecules; moreover, we probed the presence of different
components for the relaxation process of bulk and
hydrating water3.
In the present work, the study of sugar-water systems is
extended to the analysis of different mono- and
polysaccharide solutions. DRS spectra of glucose,
fructose, trehalose and dextran aqueous solutions have
been analyzed in terms of water and sugar relaxation
processes, together with damped harmonic oscillators
describing the bending (∼50 cm-1) and stretching (∼180
cm-1) of O-H⋅⋅⋅O structures in the low-frequency Raman
spectrum. The comparison of the effect of different
carbohydrate systems on the properties of water
dynamics and structure is performed and discussed.
78
isomerization. When the arylolefins exist in solution as
mixtures of equilibrated conformers, an interesting
selectivity in the adiabatic photoisomerization of a
specific conformer of the cis compounds can be often
evidenced; in particular, the adiabatic formation of the
excited 1,3trans* isomer is peculiar to the s-trans rotamers
whereas the s-cis rotamers are prompted to photocyclize.
Also the interconversion among different rotamers in the
excited states was observed in some cases against the
NEER (non equilibration of excited rotamers) principle.
centred at about 16 Å. The gravimetric analysis of H2
adsorption at 77 K over the 0 – 10 bar pressure range
shows that St-DVB can reversibly adsorb at 77 K up
to ca. 1.3 H2 wt% at 1 bar and 1.8 wt% at 10 bar
(Fig.1) in good agreement with literature data for
other hypercrosslinked polymers [2].
2 ,0
H2 uptake (wt %)
1 ,5
P 2.10
1 ,0
0 ,5
0 ,0
FTIR spectroscopy and thermodynamics of
hydrogen adsorbed in a cross-linked polymer
0
2
4
6
8
10
P re s s u re (b a r)
Fig. 1. Gravimetric H2/St-DVB adsorption isotherm at 77 K
Olena Zavorotynska, Giuseppe Spoto, Jenny Vitillo,
Alessandro Damin, Francesca Bonino and Adriano
Zecchina.
Dipartimento di Chimica IFM and NIS Centre of
Excellence, Via Giuria 7, I-10125 Torino E-mail:
[email protected]
IR experiments consisted of three steps. In the first step
(spectra 1-7 on the Fig.2a) H2 (typically 30 mbar) was
dosed at 300 K and spectral series recorded upon
gradually decreasing the temperature down to 20 K while
simultaneously monitoring the gas phase equilibrium
pressure. Following this procedure, bands first appear at
70 K at 4112, ca. 4680 cm-1 , and ca. 4445 cm-1 which
shift at higher frequency (9.5-9.7 cm-1) with lowering the
T to 20K. We assign the first two manifestations to the
Q(1) (pure vibrational) and S (1) (roto-vibrational)
transitions of adsorbed ortho-molecules and the third very
weak component at 4445 cm-1 to the S(0) mode of the
less abundant para-H2 species. The aproximate ratio in
the intensities of two strong bands and the weak one (3:1)
reflects the natural ratio of ortho and para species in
hydrogen gas. The site-specific adsorption enthalpy,
calculated from these VTIR measurements, is ca. 2.5 kJ
mol-1. This weak interaction is the result of the specific
physisorption of H2 on the the aromatic part (phenyl
rings) inside the St-DVB micro-cavities of the polymer.
This interaction is also responsible for the infrared
activation of ν (H-H) mode (Q1) and its shift about - 40
cm-1 with respect with hydrogen gas. In the second step
(8-12, Fig.2a) spectra were recorded at fixed time
intervals while keeping constant the temperature (20 K)
and the H2 equilibrium pressure of the H2/St-DVB
system. This procedure allowed to investigate the change
in composition of the adsorbed phase in terms of orthoand para-H2. In the last step (Fig. 2b) the H2/St-DVB
system was progressively outgassed at constant
temperature (20 K). H2 adsorption on St-DVB is fully
reversible at 20 K, as demonstrated by the fact that all the
above manifestations readily disappear upon decreasing
the H2 equilibrium pressure.
Singling out of safe and efficient storage methods still
represents an open problem which needs to be solved in
view of the widespread use of hydrogen as energetic
vector. Among the envisaged technologies [1] reversible
adsorption on microporous solids is in principle simple
and inexpensive, although yet inadequate to meet the
stringent DOE (U.S. Department of Energy) targets for
on board hydrogen storage systems. The method is based
on dispersive interaction between the H2 molecule and
the surface of the adsorbent, and its effectiveness is
essentially depending on (i) the energetic of interaction,
which influences the optimal storage temperature, and (ii)
the surface extension, which relates to the amount of
stored gas. Among the investigated materials polymers of
induced (by post-synthesis crosslinking procedures) or
intrinsic porosity (because of the use of proper
monomeric units) have attracted recent interest because
of promising adsorptive properties (up to 3 H2 wt%) [2].
Noteworthy, the data published up to date present only
gravimetric analysis of the amount of hydrogen stored in
these materials, while the information on the physical
nature and the thermodynamics of the interaction
between hydrogen molecules and polymer is copletely
missing. With the aim of contributing to fill this gap in
this work we have investigated by means of infrared
spectroscopy at temperature variable between 300-20 K
(VTIR method) the interaction of H2 with commercial
crosslinked
polymer
(St-DVB
poly(styrene-codivinylbenzene) from Aldrich). VTIR can in fact allow to
evaluate the adsorption energy from the optical isobars
[3] and to investigate the nature of the interaction from
the pertrubation of the vibrational modes of adsorbed H2
with respect to gas phase.
Surface area, pore volume and pore size distribution of
St-DVB
were
obtained
by
N2
adsorption
measurements carried out at 77 K. The calculated BET
surface area results to be 920 m2 g-1 with a broad pore
size distribution covering the 6 – 40 Å range and
79
0,4
Absorbance Units
catalises the reaction between the products quinol and
ferricytochrome, restoring the initial situation, with the
net result of proton translocation and gradient formation
across the membrane that will be used to drive the ATP
synthesis from ADP and phosphate.
RCs are readily extracted and purified form the their
native environment, the so called intracytoplasmatic
membrane. The result is a micellar solution in which the
RC photocycle can be realised adding external pool of
electron donors and acceptors in the appropriate redox
state. A commonly used electron donor is the ferrocene,
an organometallic compound containing a ferrous ion,
with a midpoint potential of 400 mV capable of reducing
the oxidised primary donor (Em = 450 mV) in the
millisecond timescale. The widespread use of such
chemical is due to 1) the stability of reduced form in
aqueous solution, 2) the lack of proton uptake or release
upon redox, 3) the negligible absorption changes upon
oxidation in the visible spectrum. The oxidised form of
ferrocene, the ferrocenium ion, and the quinol produced
after double light activation of the RC, undergo to a
short-circuit reaction in which the quinone is restored.
The mechanism of this reaction has been investigated
using either the native UQ10 or its water-soluble analogue
ubiquinone-0. In the latter case the reaction is mediated,
at physiological pH, by the mono-deprotonated form of
the quinol, and the reactant diffuse and equilibrate in the
solution bulk before the reaction. The situation is less
straightforward in the case of the UQ10, where the
reaction takes place in an heterogeneous system, namely
the micellar phase for the quinol and RC and the aqueous
phase for the ferrocenium. Is such system the neutral
form of the quinol appears to be involved in the redox
reaction and the surface charge of the RC modulates the
rate of the redox reaction.
(b)
(a)
12
11
10
9
8
0,2
7
6
5
4
3
2
0,0
1
4750
4500 4200
4100
-1
W avenum ber (cm )
4000
4750
4500 4200
4100
4000
-1
W avenum ber (cm )
Fig. 2. Infrared spectra of H2 adsorbed on St-DVB
To further supports the hypothesis of a specific
adsorption of the H2 molecules on the phenyl groups
inside the St-DVB micropores we have performed
theoretical calculations concerning the interaction of
dihydrogen
with
the
benzene
ring.
Good
correspondence between the calculated shift of the
anharmonic frequency of the ν(HH) mode of the
H2/C6H6 adducts (-33 cm-1) and the experimental value
for the H2/St-DVB interaction (-37 cm-1 for the Q(0)
band) was obtained. The calculated energy of
interraction (4.2 kJ mol-1) slightly overstimated with
respect to the experimental value of 2.5 kJ mol-1
observed.
Thus, VTIR technique, applied in this study shows
that the H2/St-DVB interaction primarily involves
specific weak (adsorption energy ca. 2.5 kJ mol-1)
adsorption of the H2 molecule on the phenyl rings and
gives rise to well defined vibrational and vibrationrotational IR manifestations never reported before for
the hydrogen adsorption on polymeric materials.
F. Milano, L. Gerencsér, A. Agostiano, L. Nagy, M. Trotta, and
P. Maróti, “Mechanism of Quinol Oxidation by Ferricenium
Produced by Light Excitation in Reaction Centers of
Photosynthetic Bacteria” J. Phys. Chem., Web Release Date:
30-Mar-2007
A. Agostiano, F. Milano and M. Trotta, “Investigation on the
detergent role in the function of secondary quinone in bacterial
reaction centers”, (1999) Eur. J. Biochem., 262, 358±364
1. Züttel A.. Naturwiss. 2004, 91, 157-172.
2. McKeown N., Budd M.P., and Book P. Macromol. Rapid
Commun. 2007, 28, 995-1002.
3. Spoto G., Bordiga S., Zecchina A., Cocina D., Gribov E.N.,
Regli Catal. Today 2006, 113, 65-80.
P 2.11
P 2.12
Quinol re-oxidation in the Reaction Center
photocycle in vitro
Studio di processi di binding a carico di cellule
batteriche mediante spettroscopia ATR-FTIR
differenziale
Nicola De Nicolò, Péter Maróti, László Nagy, Massimo
Trotta, Francesco Milano and Angela Agostiano.
Istituto per i Processi Chimico Fisici – sede di Bari, c/o
Dipartimento di Chimica – Via Orabona, 4 – 70124 Bari,
[email protected]
Livia Giottaa, Disma Mastrogiacomoa, Francesca
Italianob, Angela Agostianob,c, Francesco Milanob,
Massimo Trottab
a
Dipartimento di Scienza dei Materiali, Università del
Salento, Strada Provinciale per Monteroni - 73100
Lecce, [email protected]
b
CNR - Istituto per i Processi Chimico-Fisici, Sezione di
Bari, c/o Dipartimento di Chimica, via Orabona, 4 70124 Bari
c
Dipartimento di Chimica, Università degli Studi di Bari,
via Orabona, 4 - 70124 Bari
The energy associated to the solar radiation is
converted in chemical energy available for living
organisms during the photosynthesis. The main actor in
this process is the so called photosynthetic reaction centre
(RC), a membrane-bound pigment-protein complex in
which the absorption of a photon promotes a charge
separation reaction that would be otherwise energetically
unfavourable. In the photosynthetic bacterium
Rhodobacter sphaeroides the net reaction after the
absorption of two photons is the double reduction of a
loosely bound ubiquinone-10 (UQ10) and the oxidation of
two molecules of ferrocytochrome c2. Another
transmembrane protein, the cytochrome bc1 complex,
Diversi microrganismi presentano interessanti capacità
bioassorbenti nei confronti di sostanze tossiche e
risultano pertanto interessanti per lo sviluppo di tecniche
di risanamento di siti inquinati (bioremediation)1,2. In
particolare è stato dimostrato che una ampia varietà di
80
hit by a light flash, the charge separated state D+QB− (or
D+QA− in the presence of QB inhibitors) is produced.
Here D is the primary donor, a bacteriochlorophyll dimer.
In the presence of a suitable electron donor to D, a
relatively stable semiquinone is formed. The properties of
the two semiquinones are mainly modulated by the
protein environment, but fine adjustments are achieved
by the interaction with the protein surrounding, namely
the lipidic bilayer. We have reconstituted the RC in
liposomes made by different and physiologically
important phospholipids and recorded the spectra of the
semiquinones with the aim of study protein-lipid
interactions that are involved in the fine tuning of these
key intermediates.
ceppi batterici è in grado di immobilizzare metalli pesanti
sulla superficie cellulare esterna. La parete cellulare e la
membrana esterna (per i Gram-negativi) presentano
infatti una struttura chimica molto complessa, ricca di
gruppi funzionali che manifestano elevata affinità per i
protoni e per diversi cationi metallici tossici. Allo scopo
di selezionare i ceppi più versatili ed eventualmente
realizzare un miglioramento dei microrganismi basato
sull’ingegneria genetica, è fondamentale identificare i siti
di binding maggiormente coinvolti nell’immobilizzazione
dei metalli pesanti..
Le transizioni energetiche nell’ambito dei livelli
vibrazionali delle molecole, promosse dalla radiazione
elettromagnetica infrarossa, sono fortemente influenzate
dall’intorno chimico risultando sensibili ad eventi di
binding. La spettroscopia infrarossa in riflettanza totale
attenuata (ATR) è stata dunque utilizzata con successo
per delucidare la natura chimica dei gruppi funzionali
protonabili, responsabili dell’immobilizzazione di Co2+ e
Ni2+ sulla superficie esterna di Rhodobacter
sphaeroides3, un microrganismo fototrofo Gramnegativo, appartenente alla famiglia dei batteri rossi non
sulfurei. L’utilizzo di una cella in flusso e la modalità
differenziale di acquisizione degli spettri ha permesso di
sviluppare un protocollo altamente efficace per l’analisi
di sottili biofilm batterici e di rivelare con estrema
sensibilità gli eventi di binding a carico delle strutture
cellulari esterne.
P 2.14
The hydrophobic chain length of phospholipids
influences the functioning of photosynthetic
Reaction
Centres
reconstituted
in
proteoliposomes.
M. Trottaa, F. Milanoa, N. De Nicolòb, L. Giottac, L.
Nagyd, P. Marotid and A. Agostianoa,b
a
CNR – Istituto per i Processi Chimico Fisici, and
b
Dipartimento di Chimica Università di Bari;
c
Dipartimento di Scienza dei Materiali - Università di
Lecce; dDepartment of Biophysics – University of Szeged
– Szeged (Hungary)
1. Malik, A.; Environment International, 2004, 30, 261 - 78. 2.
Munoz, R.; Alvarez, M.T.; Munoz, A.; Terrazas, E.; Guyesse,
B.; Mattiasson, B.; Chemosphere, 2006, 63, 903 – 11. 3.
Buccolieri, A.; Italiano, F.; Dell’Atti, A.; Buccolieri, G.; Giotta,
L.; Agostiano, A.; Milano, F.; Trotta, M.; Annali di Chimica,
2006, 96, 195 - 203
The photosynthetic Reaction Centre (RC) is a
transmembrane pigment-protein complex where the
energy associated to the electromagnetic solar radiation is
converted into chemical energy in the form of a charge
separated state. Following absorption of a photon the
bacteriochlorophyll dimer (D) reaches its singlet excited
state (D*) and then transfers an electron through a chain
of cofactors to the final electronic acceptor QB. In
absence of electron donors to D, a charge recombination
reaction occurs with a lifetime in the seconds timescale,
strongly influenced by the protein environment. The
membrane-spanning portion of the RC is about 35 Å long
and is normally embedded in the intracytoplasmic
membrane where the most representative phospholipid is
palmitoyl-oleoyl-phosphatidylcholine (POPC) with side
chains of 16 (saturated) and 18 (monounsaturated) carbon
atoms (nc) forming a 44 Å thick bilayer. To assess the
effect of a complete or partial covering of the
transmembrane portion, RC have been reconstituted in
liposomes formed by 1,2 diacyl – phosphatidylcholine
with nc spanning from 9 to 14, ensuring that the bilayers
formed are in the liquid-crystalline phase. RCs embedded
in POPC proteoliposome, showing a charge
recombination lifetime of 2.2 s, was taken as a reference
system. A discontinuity in the charge recombination
reaction lifetime was found between nc = 12 and nc = 14
corresponding to a bilayer thickness of 32 and 37 Å
respectively.
P 2.13
Does the lipid environment influence the spectral
and kinetic properties of semiquinones in
bacterial photosynthetic reaction centres?
F. Milanoa, E. Altamurab, A. Agostianoa,b, L. Giottac, L.
Nagyd, P. Marotid and M. Trottaa.
a
CNR – Istituto per i Processi Chimico Fisici, and
Dipartimento di Chimica Università di Bari;
c
Dipartimento di Scienza dei Materiali - Università di
Lecce; dDepartment of Biophysics – University of Szeged
– Szeged (Hungary)
b
Quinones perform a key role in the energy conversion of
biological systems, coupling oxydation/reduction
reactions to proton uptake or release across membranes.
In bacterial photosyntesis a cyclic electron flow occurs
between the Reaction Centrer (RC), the bc1 complex and
the cytochrome c2; this movement of electrons is
accompanied by a net flow of protons from the
periplasmic to the cytoplasmic space. Electrons are
shuttled beteween the membrane-spanning RC and bc1
complex by the hydrophobic ubiquinone-10 (UQ10). In
the RC crystal structure two molecules of UQ10 are
found in distinct binding sites, termed QA and QB. The
quinone in the QA pocket acts as a single electron carrier
and is firmly associated to the protein, while the one in
the QB pocket can undergo to double reduction and
protonation and is loosely bound. When isolated RC are
81
size and wavelength, and on the material microstructural
characteristics and defects.
The hybrid sol-gel synthesis is an attractive, simple,
cheap and very versatile way to produce materials with
desired shapes and properties. The wide possibility to
vary the process parameters, like precursors, type of
catalysis and chemical route of synthesis, permits one to
control also the microstructure and the macroscopic
properties of final samples.
The use of Glycidoxypropyltrimethoxysilane (GPTMS)
and silica-based Nanobuilding Blocks (NBB) allows
preparing materials with good optical properties,
controlled heterogeneity and scratch and abrasion
resistance.
Different sol-gel matrices, based on GPTMS and NBB,
have been prepared in order to study their laser damage
resistance. The possibility of varying the catalyst and
precursors or the synthesis procedure allows obtaining
materials with similar chemical composition but different
microscopical properties. By this way, it is possible to
study the laser damage threshold of these samples,
understand effects and causes of the damage and find the
way to enhance and optimize the laser damage resistance,
useful in non-linear optics.
P2.15
New Sol-Gel Hybrid Materials for High Energy
Applications in Nonlinear Optics
I.Fortunatia; R.Signorinia; R.Bozioa; G.Brusatinb;
M.Guglielmib; S.Dirèc
a
Dip. di Scienze Chimiche, Univ. di Padova, via Marzolo
1, I-35131, Padova, Italy, [email protected]
b
Dip. di Ing. Mecc.-Sett. Materiali, Univ. di Padova, via
Marzolo 9, I-35131, Padova, Italy
c
Dip di Ingegneria dei Materiali e Tecnologie Industriali,
Univ. di Trento, via Mesiano 77, I-38050 Trento, Italy
Organic-inorganic hybrid materials, composed of
inorganic oxide structures and interpenetrated crosslinked organic polymers, are promising candidates for
electro/optical applications, combining the most
important glass-like and polymer-like properties. This is
particularly true when large laser power density is used,
in fact these materials show high laser damage resistance
compared with that of polymeric systems.
To our knowledge, a deep study of the effects and causes
of hybrid materials laser damage has never been done.
The mechanisms of optical damage depend on a
multiplicity of factors both on the laser source
experimental parameters, such as pulse duration, beam
82
SEZIONE
COLLOIDI ED INTERFASI
83
P 3.1
CH2OH
CH2OH
THERMAL
CHARACTERIZATION
OF
Br-
H
N
ANALYSIS
C16H33
C16H33 H
SOME
H
N
C16H33
3
CATIONIC LIPOSOMES
Br-
4
Mixed binary systems composed of DMPC and cationic
Bonicelli M. G.a, Giansanti L.b, Mancini G.c, Pascale
surfactants at different molar ratios (8/2, 7/3, 6/4, 5/5)
F.d
have been calorimetrically characterized at the aim of
a,d
Dipartimento
Ingegneria
Chimica,
Materiali,
correlating the mo
Ambiente, Sapienza Università di Roma, Via del Castro
lecular
Laurenziano 7, 00161 Roma, Italy
physicochemical
b,c
deconvolution analysis of DSC data to obtain bilayer
Dipartimento Chimica Organica, Sapienza Università
structure
of
features
the
of
components
the
to
the
aggregates.
The
di Roma, Piazzale Aldo Moro5, 00161 Roma, Italy
partition function based on the method described by
Differential scanning calorimetry (DSC) is a rapid
Freire and Biltonen
simple thermodynamic technique which may be used to
organization and fluidity of hydrocarbon chains.
study lipid thermotropic phase behaviour in biological
Furthermore, with careful analysis and interpretation,
membranes and in their model systems, such as closed
calorimetric experiments can directly yield fundamental
lipid bilayers entrapping an internal aqueous phase
thermodynamic
(liposomes) formed by phospholipid. The structure,
involved, such as phase separation and domain formation.
3
provided information about lipid
information
about
the
processes
fluidity, transport properties, surface potential of these
model systems can be systematically investigated at the
1
aim of understanding the more complex biomembrane
J.H., Biophysical Journal, 80 (2001), 1819-1828
systems.
1
2
We have determined the gel to liquid crystalline phase
transition
Leidy C., Wolkers W.F., Jorgensen K., Mourtisen O.G., Crowe
temperature,
calorimetric
∆H
and
Scipioni, M. Venanzi, Chirality, 15(5) (2003), 441-447
the
3
cooperativity of the process in mixed liposomes
composed
by
S. Borocci, F. Ceccacci, L. Galantini, G. Mancini, D. Monti, A.
E. Freire, R. Biltonen, Biochimica et Biophysica, 514 (1978),
54-68 (1978)
1,2-dimyristoyl-sn-glycero-3-
phosphatidylcoline (DMPC) and synthetic cationic
surfactants
1,
(1S,2S)-N-hexadecyl-N-methylprolinolinium bromide, 2,
(1R,2S)-N-hexadecyl-N-methylprolinolinium bromide, 3,
N-hexadecyl-L-prolinolinium
bromide,
and
P 3.2
4,
N,N-dihexadecyl-L-prolinolinium bromide.2
Effect of dopant (Nd, Er, Eu and Ce) amount on
O
O
O
O
O
P O
yttrium
N+
aluminum
garnet
nanoparticles
structure
O-
Eugenio Caponettia, Delia Chillura Martinoa, Maria Luisa
Saladinoa, Stefano Enzob, Giulio Ibbab
O
DMPC
a
Dipartimento di Chimica Fisica “F. Accascina”,
Università di Palermo and INSTM-Udr Palermo,Parco
N
H3C
H
Br
-
N
C16H33
C16H33
1
d’Orleans II, Viale delle Scienze pad.17, Palermo
CH2OH
CH2OH
H
Br
90128,[email protected]
-
b
Dipartimento di Chimica, Università di Sassari and
CH3
INSTM-Udr Sassari, Via Vienna 2, Sassari 07100
2
Hydroxides precursors synthesized by co-precipitation
method, were calcined at different temperatures from 900
84
to 1100°C for one hour to produce the YAG
Il recente sviluppo della chimica supramolecolare ha
nanopowders. Further, to obtain information on the
ravvivato la possibilità di ottenere polimeri per mezzo di
degree of solubility of some lanthanide ions, YAG
associazioni reversibili, ovvero polimeri supramolecolari
3+
3+
realizzati attraverso l’associazione di monomeri mediante
powders with different doping amounts of Nd , Er ,
3+
3+
Eu and Ce have been prepared.
interazioni non covalenti. Il principale vantaggio di questi
All samples were characterized by Field Emission Gun-
polimeri rispetto a quelli covalenti risiede nel fatto che in
Scanning Electron Microscopy, Thermo-Gravimetry and
essi il processo di polimerizzazione è rappresentato da
Differential Thermal Analysis, X-Ray Diffraction and
equilibri
Surface Area Analysis. The effect of thermal treatment
termodinamiche, possono essere facilmente condizionati,
on the powders structure was systematically inspected.
fornendo la possibilità di governarne le proprietà
TG and DTA experiments were performed from room
dall’esterno. In particolare polimeri supramolecolari host-
temperature up to 1500 °C; the presence of exo- and
guest, alcuni dei quali mostrano interessanti applicazioni
endo-thermal events was found to accompany phase
potenziali, sono stati ottenuti utilizzando le proprietà
transformation phenomena.
ospitanti della ciclodestrina [1-4]. Con opportuni guests
che,
essendo
funzione
di
variabili
of
queste molecole danno origine a composti di inclusione
aggregation features in the powders with a rounded
molto stabili che, impiegati nella polimerizzazione,
morphology.
dovrebbero garantire il raggiungimento di elevati gradi di
Analysis of XRD patterns confirmed the formation of
polimerizzazione. Tuttavia, molto spesso sembrano
YAG phase. The lattice parameter of garnet phase
formarsi strutture cicliche o complessi chelati che
depends on the specific doping, its amount and
prevengono la formazione di polimeri lunghi [3,4].
temperature treatment.
Sebbene una grossa mole di lavoro sia stata dedicata alla
For each dopant there is not a regular trend. In all case at
preparazione di nuovi polimeri supramolecolari host-
low concentration lanthanide ions substitute for yttrium
guest, manca ancora una descrizione dettagliata della loro
ions in the dodecahedral sites of the garnet structure. On
struttura in soluzione e alcuni aspetti del quadro piuttosto
increasing the temperature a reduction of the YAG cell
complesso, rappresentato dalle proprietà di aggregazione
parameter is observed probably due to defect release in
di questi sistemi, restano oscuri. Per questa ragione è
the garnet structure. In addition to this, the formation of
stato effettuato uno studio strutturale su un copolimero
other crystalline phases such as YAH, YAM and YAP are
supramolecolare formato da dimeri di β-ciclodestrina (β-
observed.
CD2) e dimeri di Adamantano (Ad2), combinando
FEG-SEM
observations
showed
the
presence
esperimenti di small angle X-ray scattering e light
scattering con simulazioni di dinamica molecolare (MD)
e Monte Carlo (MC). Dapprima sono state studiate le
soluzioni dei monomeri attraverso le sole misure di
P 3.3
scattering.
Successivamente,
è
stato
analizzato
il
complesso generato da una molecola di Ad2 e due
Studio strutturale di polimeri supramolecolari
molecole di β-ciclodestrina correlando risultati di
host-guest
scattering e simulazioni di MD, per caratterizzare la
a
a
connessione host-guest. Infine, una interpretazione
Luciano GALANTINI , Claudia LEGGIO , Nicolae
a
a
dettagliata dei dati di scattering del polimero è stata
Viorel PAVEL , Massimiliano ANSELMI , Alfredo DI
a
b
b
NOLA , Aida JOVER , Francisco MEIJIDE , Victor
realizzata attraverso simulazioni MC. Quest’ultime sono
Hugo SOTO TELLINIb, José VÁZQUEZ TATOb
state condotte su un singolo aggregato supramolecolare e,
a
Dipartimento di Chimica, Università La Sapienza, P.le
vista la forma peculiare della catena polimerica,
A. Moro 5, 00185 Roma, [email protected]
utilizzando la struttura molecolare completa, senza
b
Departamento de Química Física, Facultad de Ciencias,
ricorrere a modelli semplificati di catena polimerica. Il
Universidad de Santiago de Compostela, Avda. Alfonso X
confronto delle simulazioni, con e senza interazioni di
El Sabio s/n, 27002 Lugo, Spain
volume escluso, indicano che il polimero è vicino alla
85
condizione teta. Minimizzazioni mediante metodi di
excellent physical, chemical and mechanical properties
Reverse MC mostrano che il polimero presenta una forma
shown by chitosan, make it a good candidate for using in
ripiegata ma non si chiude in strutture cicliche, come
drug delivery systems, medical field, as component in
generalmente ipotizzato per questo tipo di oligomeri.
cosmetic products, agriculture and water treatment 3-6.
Tuttavia, è stato stimato un grado di polimerizzazione di
One of the most attractive features of chitosan that has
circa 8 (4 Ad2 e 4 β-CD2) che non manifesta alcuna
cap-tured the attention of researchers from both academic
dipendenza dalla concentrazione.
and industrial areas, is the capability to form semirigid
films and hydrogels with good swelling properties 1. This
1. Y. Liu, H. Wang, P. Liang, H.-Y. Zhang, Angew.
characteristic, together with its protonable nature, has
Chem., Int. Ed., 43, 2690 (2004).
allowed to form pH-sensitive swellable chitosan gels,
2. V. H. Soto, A. Jover, J. Carrazana, L. Galantini, F.
used as stomach-targeted drug delivery systems
Meijide, J. Vázquez Tato, J. Am. Chem. Soc., 128, 5728
7,8
, and
chitosan complexes useful in gene delivery applications 9.
(2006).
In order to formulate new biomaterials with more
3. Y. Hasegawa, M. Miyauchi, Y. Takashima, H.
appealing characteristics, chitosan is often used in blend
Yamaguchi, A. Harada, Macromolecules, 38, 3724
with other polymers or in combination with surfactant
(2005).
substances. The use of polymer blends allows, in
4. K. Ohga, Y. Takashima, H. Takahashi, Y. Kawaguchi,
principle, having new gels with properties which are
H. Yamaguchi, A. Harada, Macromolecules, 38, 5897,
different from those of the single components
(2005).
10,11
,
whereas polymer-surfactant complexes, where present,
can significantly modify the characteristics of solutions
and
hydrogels
(for
instance
improving
swelling
properties) opening new possibilities of applications
Among
P 3.4
poly(vinylpyrrolidone)
is
biocompatibility.
On
hydrogels formed by Chitosan, in the Presence
,
Paduanoa,
Luigi
(SANS),
Studi
di
Napoli
Federico
CSGI
–
structure
of
chitosan
(PVP)
and
hydrogels,
paramagnetic
and
swelling
resonance
degree
(EPR),
measurements.
According to the SANS results, the structure of these
II,
hydrogels
Dipartimento di Chimica, via Cinthia, 80126 Napoli,
[email protected];
electron
intradiffusion
Roberto Sartorioa
degli
the
of the combined use of small angle neutron scattering
Henrich
Frielinghausb, Gerardino D’Erricoa, Ornella Ortonaa,
Università
bases,
chemically crosslinked, has been investigated by means
Sodium decylsulfate
Mangiapiaa
these
chitosan/poly(vinylpyrrolidone)
and Absence of Poly(vinylpyrrolidone) and
a
polymers,
.
recognized to be a good candidate due to its good
Physico-Chemical and Structural Properties of
Gaetano
the
12
may
be
described
in
terms
of
an
inhomogeneous structure composed by polymeric-rich
Consorzio
and polymer-poor regions. The polymer rich region,
interuniversitario per lo sviluppo dei Sistemi a Grande
whose correlation distance ζ
Interfase
is ranged between ~ 600
Å and ~ 850 Å, are in turn characterized by the presence
b
Institut für Festkörperforschung, Forschungszentrum
of a network formed by the chemical crosslinks (see
Jülich, D-52428 Jülich, Germany; JCNS – Jülich Centre
figure 1), with a mean correlation distance ξ ~ 90 Å .
for Neutron Science.
Chitosan is a polycationic biopolymer obtainable from
partial enzymatic or alkaline deacetylation of chitin, a
natural and abundant polysaccharide, occurring in
crustaceous shells and insect exoskeletons, often in
association with proteins and minerals 1,2.
The good biocompatibility, natural availability, and the
86
8. Anandan, R. N., P. G. V.; Mathew, S.; Journal of Pharmacy
and Pharmacology, 2004, 56, 265.
9. Borchard, G.; Advanced Drug Delivery Reviews, 2001, 52,
145.
10.
Sionkowska,
A.;
Journal
of
Photochemistry
and
Photobiology, B: Biology, 2006, 82, 9.
11. Kim, S.; Nimni, M. E.; Yang, Z.; Han, B.; Journal of
Biomedical Materials Research, Part B: Applied Biomaterials,
Figure 1 – Schematic representation of the polymer rich
region of Chitosan/PVP hydrogels. Mean mesh size ξ of
the network is also indicated.
2005, 75B, 442.
The structure of chitosan and chitosan/PVP hydrogels has
Biointerfaces, 2005, 42, 147.
12. Sagnella, S.; Mai-Ngam, K.; Colloids and Surfaces, B:
also been analyzed in the presence of sodium decylsulfate
(C10OS) micelles that could provide a multidomain
system useful, in principle, for drug delivery applications.
Both SANS and EPR measurements have shown that
sodium
decylsulfate
(C10OS)
micelles
do
P 3.5
not
significantly interact with both the gels, being free to
move inside the polymer networks. Finally, intradiffusion
Self-assembly
and swelling degree measurements, have shown an
nanocrystals into ribbon-like and globular
improved hydrophilicity of chitosan/PVP gels, further
agglomerate
magnified by the presence of C10OS surfactant.
application.
In
light
of
the
results
obtained,
chitosan
and
of
starch
structures
stabilized
for
Ag
biosensors
A. Serra, D. Manno, E. Filippo, T. Siciliano, A. Tepore
chitosan/PVP hydrogels appear as possible matrices for
building up systems for drug delivery of both hydrophilic
Dipartimento di Scienza dei Materiali – Unità CNISM
and hydrophobic active molecules. These matrices can be
Università del Salento – Via Monteroni, 73100 Lecce
attained by simple addition to the gel of an appropriate
amount of amphiphilic substances, such as a surfactant,
Metal and semiconductor nanoparticles are of great
forming a swellable multi-domain system able to be used
importance due to their potential applications in emerging
as lipophilic and hydrophilic reservoir for the releasing of
areas of nanoscience and technology. Size, shape, and
small molecules.
surface morphology play pivotal roles in controlling the
physical, chemical, optical, and electronic properties of
1. Ravi Kumar, M. N. V.; Muzarelli, R. A. A.; Muzzarelli, C.;
these nanoscopic materialsi. Preparation of nanoparticles
Sashiwa, H.; Domb, A. J.; Chemical Reviews, 2004, 104, 6017.
generally involves the reduction of metal ions in solutions
2. Hudson, S. M.; Smith, C. Polysaccharides: chitin and
or in high temperature gaseous environments.
chitosan: chemistry and technology of their use as structural
Most of the synthetic methods reported to date rely
materials. In Biopolymers from Renewable Resources; Kaplan,
heavily on organic solvents. This is mainly due to the
D. L., Ed.; Springer: Berlin, Germany, 1998; pp 96.
hydrophobicity of the capping agents used. There have
3. Sakkayawong, N.; Thiravetyan, P.; Nakbanpote, W.; Journal
been approaches reported for the synthesis
of Colloid and Interface Science, 2005, 286, 36.
soluble metal nanoparticles. The majority of methods
4. Yan, W. L.; Bai, R.; Water Research, 2005, 39, 688.
reported to date use reducing agents such
5. Shi, X. Y.; Tan, T. W.; Journal of Bioactive and Compatible
as hydrazine, sodium borohydride (NaBH4), and dimethyl
Polymers, 2004, 19, 467.
formamide (DMF). All of these are highly reactive
6. Ham-Pichavant, F.; Sebe, G.; Pardon, P.; Coma, V.;
chemicals
Carbohydrate Polymers, 2005, 61, 259.
biological risks.
7. Siegel, R. A.; Falamarzian, M.; Firestone, B. A.; Moxley, B.
In this work we propose a preparation method of silver
C.; Journal of Controlled Release, 1988, 8, 179.
nanoparticles and nanowire based onto hydrothermal
87
and
pose
potential
of H2O-
environmental
and
synthesis that uses solvent medium, reducing agent, and
capping agent that are all environmentally benign and
(111)
Intensity (a.u.)
nontoxic material.
In the present approach, H2O is utilized as the
environmentally
benign
solvent
throughout
the
(200)
preparation. The sugar, β-D-glucose, is used as the
reducing agent. With gentle heating, this system is a mild,
34
36
38
40
42
44
46
48
50
2θ
renewable, inexpensive, and nontoxic reducing agent.
The final, and perhaps most important, issue in the
Figure 2 XRD pattern of Ag-starch nanocomposite.
preparation of nanoparticles is the choice of starch as the
The peaks correspond to 111 and 200 planes of the cubic
capping material used to protect or passivate the
phase of metallic silver
nanoparticle surface.
Analyses of the optical properties of the silver
The resulting nanocomposites were investigated using
nanocomposite aqueous dispersions have been performed
structural, optical and morphological methods. XRD
by UV-Vis spectroscopy.
spectra of the nanocomposites confirmed the presence of
1.6
Absorbance (a.u.)
nanostructured silver (cubic phase) in the matrix. High
Resolution Transmission Electron Microscopy (HREM)
methods showed that the nanoparticles are mostly
spherical in shape and aggregate in nano-ribbon and
globular formation (figure 1).
1.2
experimental
0.8
0.4
fitting curve
200
400
600
800
λ (nm)
Figure 3
UV-Vis spectrum obtained onto the solution Agstarch nanocomposite
In Figure 3 is visible a broad peak in the 400-500 nm
spectral range. This is due to surface plasmon resonance
phenomena of the electrons in the conduction bands of
silver and also indicate the formation of silver colloids
with nanometer-sized dimensions. To interpret the
absorption spectrum of silver nanoparticles, we used the
light scattering theory of Mieii and free electron theory of
Drudeiii. The experimental absorption coefficient vs.
Ag
wavelength plots have been fitted with modified Mie
nanocrystals; (b) nanoparticles spherical in shape and aggregate
theory, taking into account the finite size distribution of
in nano-ribbon.
the particles in colloidal solution. The reported fit has
Figure 1
(a)
A
typical
globular
agglomerate
of
been obtained for a volume fraction of
84 % of
X-ray diffraction (XRD) measurements were performed
nanoparticles having mean size of 20 nm.
on a Rigaku miniflex X-ray diffractometer (Cu Kα1/2
The silver nanostructures were electrodeposited onto
radiation, λ = 0.154 nm). Figure 2 shows the XRD
suitable substrates with gold interdigital electrodes. The
spectrum of the silver- starch nanocomposite.
obtained amperometric biosensors showed an high
sensitivity to hydrogen peroxide.
88
products
10
(drilling
fluids,
personal
care
products,
pharmaceutics, building materials, paper coaters, paints,
etc.). Aqueous dispersions of such a clay contains
monodisperse nanometric disks which undergo to a sol-
S
1
gel transition.
Within this topic adsorption of homopolymer and
0.1
1
10
100
H2O2 concentration (µM)
copolymers on clay particles is relevant because
polymers can inhibit the gelation process by steric
Figure 4
hindrance [1]. Moreover, coated particles may have
Sensitivity (S) as function of hydrogen
advanced features generating novel materials like clay-
peroxide concentration.
polymer
To evaluate the faculty of a sensor to detect a particular
nanocomposites.
Particularly,
tri-block
copolymers offer the great advantage to be properly tuned
chemical speciesiv by a variation of its resistance, we
by modulating the length of the constituent blocks or by
introduced the sensitivity S defined as the absolute value
changing their architecture.
of the ratio
Therefore, we believed that it would be interesting to
∆R
S=
R
∆C
C
perform small amplitude oscillatory shear and dynamic
light scattering studies on gelation kinetics of aqueous
where ∆R is the resistance variation due to chemical
laponite dispersions in
species concentration variation ∆C. This ratio gives a
oxide)-poly(propylene oxide)- poly(ethylene oxide) tri-
measurement of the electrical response of the sensor in a
block copolymers and their homopolymers. To this aim,
close relation to the response phenomena. As evident the
the effect of the polymer hydrophilicity, the copolymer
sensitivity decreases as the concentration increases too.
molecular
weight
the presence of poly(ethylene
keeping
constant
the
hydrophilic/hydrophobic ratio, and the architecture was
investigated. The findings on the homopolymers confirm
our earlier unexpected results obtained by means of high
shear viscosity experiments [2]. Namely, the gelation
P 3.6
process is speeded up in the presence of low molecular
weight polymer and it is slowed down for higher
Kinetics of Gelation of Aqueous Laponite
molecular weights. The results in the presence of
Dispersions
Tri-block
copolymers are also unusual. As a general feature, the
Homopolymers.
copolymer slow down the kinetics of gel formation the
Rheological and Dynamic Light Scattering
effect being more important the lower the molecular
Studies
weight is.
Copolymers
in
the
and
Presence
their
of
R. De Lisi,a M. Gradzielski,b G. Lazzara,a S. Miliotoa and
N. Muratorea
a
1. De Lisi, R.; Lazzara, G.; Lombardo, R.; Milioto, S.; Muratore,
Dipartimento di Chimica Fisica “F. Accascina”,
N.; Turco Liveri, M. L.; Phys. Chem. Chem. Phys., 2005, 7,
Università degli Studi di Palermo, Viale delle Scienze,
3994 - 4001. 2. De Lisi, R.; Gradzielski, M.; Lazzara, G.;
Parco
Milioto, S.; Muratore, N.; Langmuir (submitted)
D'Orleans
II,
90128
Palermo,
Italy,
Physikalische
und
[email protected]
b
Stranski
Laboratorium
für
Theoretische Chemie, Institut für Chemie, Technische,
Universität Berlin, Straße des 17. Juni 124, 10623 Berlin,
Germany
Laponite is a low cost highly pure synthetic clay
frequently used as thickener agent of water-based
89
P 3.7
polymer as shown by the reduction of its hydrodynamic
radius.
The aggregative behavior of hydrophobically
Converging evidences are obtained by the analysis of the
modified chitosans of 10% level substitution
fluorescence spectra of pyrene, used as probe, in the
a,b
a,b
a,b
aqueous solutions of the grafted polymers and evidencing
Ornella Ortona , G. D’Errico , G. Mangiapia , L.
Paduano
a,b
how different is the environment in which pyrene is
a
Università degli Studi di Napoli “Federico II” –
located if short or long chained polymers are analyzed. In
Dipartimento di Chimica. Via Cinthia, 80126 Napoli, e-
fact, the spectra in CHIT, C5-CHIT and C6-CHIT
mail:[email protected]
solutions are quite similar among them and also similar to
b
the pyrene spectrum in water. These evidences confirm
Sistemi a Grande Interfase.
the scarce ability of these aliphatic substituents to tune
CSGI – Consorzio interuniversitario per lo sviluppo di
hydrophobic aggregation. In contrast, pyrene in the
Nowadays chitosan, obtained from partial deacetylation
presence
of
C8-CHIT,
of chitin, is becoming one of the most interesting row
solutions, gives rise to a progressive and evident
material for the actual and potential applications in
modification of the spectra resembling that of this
several fields such as waste water and drinking water
fluorescent probe in a hydrocarbon solvent.
C10-CHIT,
and
C12-CHIT
treatment, food processing, biotechnology, medical
application, agriculture. Being chitin obtained from the
crustacea carapace, chitosan is very abundant and
ecologically friendly. This is the reason why attention is
P 3.8
paid on its properties from both a technological and a
basic science viewpoint.
In the past, a quantitative reductive amination reaction of
Modeling of H2 adsorption and spectroscopic
the amino groups present in the gluco-pyranose units of
observation of the ortho-para conversion on the
chitosan, CHIT, allowed to graft to chitosan a lot of
ETS-10 titanosilicate
pendants such as aliphatic chains, ethoxylic groups, sugar
G. Ricchiardi, J. G. Vitillo, D. Cocina, G. Spoto, A.
residues and so on, modulating at will both the
Zecchina
substitution entity and the water affinity of the grafted
Dipartimento di Chimica IFM and NIS Centre of
polymer, Cn-CHIT.
Excellence,
This work is devoted to the study of the intra and inter-
Università, Via Pietro Giuria 7, 10125 Torino, Italia.
aggregation properties in acidic water of modified
Phone: +39 011 6707845. Fax: +39 011 6707855. E-
chitosan by the insertion of aliphatic chains on its
mail: [email protected]
Università
di
Torino,
INSTM
UdR
backbone.
Chitosan has been modified with reductive amination by
inserting aliphatic chains of different length, namely: C5,
INTRODUCTION
C6, C8, C10, C12 at 10% of molar substitution degree. The
The titanosilicate ETS-10 is a zeotype having chemical
physico-chemical properties of the acidic solutions of the
formula (Na,K)2TiSi5O13. Its structure is characterized by
polymers have been studied through Newtonian viscosity
12- and 7-ring channels. Only the channels formed by 12-
and by the aid of the pyrene fluorescence.
rings are permeable to diatomic molecules. In the as-
Viscosity showed that while for CHIT and C5-CHIT the
synthesized material [1] two alkali-metal cations are
viscosity behavior is quite similar highlighting that the
incorporated for every titanium atom. Four sites (I -IV)
insertion of this short aliphatic chain does not modify the
can be recognized which have an occupancy factor of 1.0
rigidity and /or the interaction with the solvent, for C6,
in ETS-10: among them, only the Na(III) is fully exposed
C8, and C10-CHIT, the increasing length of the pendant
[2].
promote a more and more efficient auto-association of the
Infrared spectroscopy has been used to study the
adsorption of hydrogen on the ETS-10, in the 300-15 K
90
temperature range. A molecular mechanics (MM) study
has been employed in order to evaluate the steric
constraints to H2 interactions with Na+ sites and to
predict coordination shells.
EXPERIMENTAL
The ETS-10 sample was supplied by Engelhard (Iselin,
NJ, USA). The infrared spectroscopic measurements
were performed by using an home made cryogenic set-up
(for a detailed description see Ref. 3). Thin self-supported
wafers of the zeolite sample were prepared and activated
0.2 a.u.
in high vacuum at 773 K for 2 h. The H2 was dosed at 15
K on the activated sample. Once the equilibrium has been
reached, the H2 gas was gradually outgassed.
4160
4120
4100
4080
W avenumber (cm )
novel forcefield for H2-H2 and H2-Na+ interactions has
Fig. 1 FTIR spectra recorded at 15 K of H2 adsorbed
been fitted to experimental electrostatic properties and ab
on ETS-10 (dashed line) and after a period of 18 h
initio PES. Periodic models with P1 symmetry have been
(solid line). Gray lines refer to intermediate elapsed
used. The complete filling of the channels has been
times. A representation of ETS-10 is also reported.
evaluated following a procedure described in the
formation is hindered on a steric basis. The simulated Na-
literature [4].
H radial distribution function of hydrogen shows three
well separated adsorption regimes: the formation of the
RESULTS AND DISCUSSION
1:1 adduct, its evolution into a 1:2 adduct and a further
The spectra of H2 adsorbed on ETS-10 at 15 K depend on
disordered layer filling all the available pore volume.
two parameters: the H2 pressure and the contact time. As
The time evolution of the spectra over a period of 18 h is
far the dependence of the pressure is concerned. at low
H2 coverage, two
4140
-1
Calculations were performed by using MM methods. A
ν H− H
shown in Fig. 1 (solid line): it consists in the gradual
disappearance of the triplet described above and the
peaks are observed at 4107 and
parallel formation of a new triplet upward shifted of
4113 cm-1. Their separation and relative intensities (3:1)
about 7 cm-1. It is noticeable the presence of clear
allow to assign them to ortho- (4107 cm-1) and para-H2
isosbestic points in Fig. 1. We think these facts can be
(4113 cm-1) (ortho:para ratio 75:25) adsorbed in Na+···H2
interpreted on the basis of an ortho to para conversion
1:1 complexes. With respect to free H2 these peaks are
process involving adsorbed H2 and due to the
downward shifted of -47 cm-1. Upon increasing the
combination of single-site reactions catalyzed by the
coverage, the original peaks are consumed and a new one
zeolite involving the whole family of adsorbed species.
appears at 4111 cm-1 with a shoulder at 4118 cm-1. In our
This is the first direct in situ observation of the catalyzed
opinion, this behavior is due to the transformation of the
ortho-para conversion of H2 on adsorbed molecules.
1:1 Na+···H2 adducts into Na+···(H2)2 complexes. Further
increase of the hydrogen pressure leads to the appearance
REFERENCES
of additional bands in the 4150-4120 cm-1 interval, as
shown in Fig. 1 (dashed line). These bands are assigned
(1) S. M. Kuznicki, US Patent 4853202, 1989.
to aspecific interactions of H2 with the ETS-10 walls
(2) A. Zecchina, C. Otero Areán, G. Turnes Palomino, F.
(4130-4120 cm-1) and to the formation of a liquid-like
Geobaldo, C. Lamberti, G. Spoto, S. Bordiga, Phys. Chem.
phase in the cavities (4150-4130 cm-1). The possible
Chem. Phys, 1999, 1, 1649.
formation of Na+···(H2)n complexes with n>2 can been
discarded on spectroscopic as well as on a theoretical
ground basis: MM simulations show in fact that their
91
(3) G. Spoto, E. N. Gribov, G. Ricchiardi, A. Damin, D.
active species become the dominant fraction of the iron
Scarano, S. Bordiga, C. Lamberti, A. Zecchina, Prog. Surf. Sci.,
species.
2004, 76, 71.
(4) J. G. Vitillo, G. Ricchiardi, G. Spoto, A. Zecchina, Phys.
Chem. Chem. Phys. 2005, 7, 3948.
P 3.9
Structure and nuclearity of active sites in Fezeolites: comparison with iron sites in enzymes
and homogeneous catalysts.
Gabriele Ricchiardi, Mickaël Rivallan, Gloria Berlier,
Fig. 1 Diferent classes of iron sites in Fe zeolites.
Carlo Lamberti, Adriano Zecchina
Università
di
Torino,
Dipartimento
di
Chimica
On the basis of the spectroscopic titration of the
Inorganica, Fisica e dei Materiali, and NIS Centre of
active sites by using NO as probe [1,2,4,5], we conclude
Excellence, Via P. Giuria 7, 10125 Torino, Italy.
that the active species on very diluted samples are
[email protected]
isolated and highly coordinatively unsaturated Fe2+
grafted to the crystalline matrix. Indication of the
constant presence of a smaller fraction of Fe2+
Fe-ZSM-5 and Fe-silicalite zeolites efficiently catalyse
presumably located on small clusters is also obtained.
several oxidation reactions which find close analogues in
The nitrosylic species have been analyzed in detail and
the oxidation reactions catalyzed by homogeneous and
the similarities and differences with the cationic, heme
enzimatic compounds [1,2]. The iron centres are highly
and non heme homogeneous counterparts have been
dispersed in the crystalline matrix and on highly diluted
evidenced. The same has been done for the oxygen
samples, mononuclear and dinuclear structures are
species formed by N2O decomposition on isolated sites
expected to become predominant. The crystalline and
[7,8], whose properties are more similar to those of the
robust character of the MFI framework has allowed to
iron
hypothesize that the catalytic sites are located in well
in
cationic
complexes
[3]
(included
the
[(H2O)5FeO]2+ “brown ring” complex active in Fenton
defined crystallographic positions. For this reason these
reaction) than to those of ferryl groups in heme and non
catalysts have been considered as the closest and best
heme counterparts.
defined heterogeneous counterparts of heme and non
heme iron complexes and of Fenton type Fe2+
1. G. Berlier, G. Spoto, S. Bordiga, G. Ricchiardi, P. Fisicaro, A.
homogeneous counterparts [3]. On this basis, an analogy
Zecchina, I. Rossetti, E. Selli, L. Forni, E. Giamello and C.
with the methane monooxygenase has been advanced
Lamberti, J. Catal., 208 (2002) 64; 2. G. Berlier, A. Zecchina,
several times. The examination of the structure,
G. Spoto, G. Ricchiardi, S. Bordiga and C. Lamberti, J. Catal.,
nuclearity and catalytic activity of the iron species
215 (2003) 264; 3. A. Wanat, T. Schneppensieper, G. Stochel, R.
obtained with various characterization techniques already
van Eldik, E. Bill and K. Wieghardt, Inorg. Chem., 41 (2002) 4;
reported in literature, we conclude that Fe-ZSM-5 and
4. A. Zecchina, M. Rivallan, G. Berlier, C. Lamberti and G.
Fe-silicalite are not the ideal samples conceived before
Ricchiardi, Phys. Chem. Chem. Phys., invited paper, submitted
and that many types of species are present, some active
(2007); 5. M.T. Nechita, G. Berlier, G. Ricchiardi, S. Bordiga
and some other silent from adsorptive and catalytic point
and A. Zecchina, Catal. Lett., 103 (2005) 33; .6. G. Mul, J.
of view. The relative concentration of these species
Perez-Ramirez, F. Kapteijn and J.A. Moulijn, Catal. Lett, 80
changes with thermal treatments, preparation procedures
(2002) 129; 7. L. Kiwi-Minsker, D.A. Bulushev and A. Renken,
and loading. Only at lowest loadings the catalytically
92
Catal. Today, 91-92 (2004) 165; 8. A. Heyden, N. Hansen, A.T.
preliminarily the presence of significant amounts of water
Bell and F.J. Keil, J. Phys. Chem. B, 110, (2006) 17096
within the micellar core, solubilization of FeCl3 occurs
without the need to add water in the micellar solution
reaching the very high solubility value, expressed as the
maximum salt-to-surfactant molar ratio, of 1.30. The
P 3.10
analysis of the FT-IR spectra of the investigated samples
leads to hypothesize that iron(III) chloride is secluded
FT-IR Study of the State of Iron(III) Chloride
within the reverse micellar core as small size melted
Clusters Confined in AOT Reverse Micelles
clusters of ionic species arising from the reactions
a
a
b
b
V. Turco Liveri , R. Biancheri , L. Ceraulo , S. Fanara ,
FeCl3 + FeCl3→ FeCl 2+ + FeCl 4−
C. Giordanoa, A. Ruggirelloa
a
Dipartimento di Chimica Fisica, Università di
FeCl3 + FeCl 4− → Fe 2 Cl 7−
Palermo,Viale delle Scienze Parco d’Orleans II, 90128
Palermo, [email protected]
followed by a strong structural rearrangement of the AOT
b
Dipartimento di Chimica e Tecnologie Farmaceutiche,
head group region surrounding the micellar core and a
Università di Palermo, via Archirafi 32, 90123 Palermo
shift of the sodium counterion from the micellar core
surface to its interior. This picture has been further
Recently, it has been shown that large amounts of some
corroborated
by
conductivity
measurements
of
hydrophilic organic and inorganic substances can be
FeCl3/AOT/CCl4 solutions as a function of the salt-to-
entrapped in almost dry reverse micelles forming small
surfactant molar ratio.
size aggregates stabilized by a monolayer of opportunely
oriented surfactant molecules. Thus, through a simple
1. Giordano, C.; Longo, A.; Turco Liveri, V.; Venezia, A. M.;
procedure and using mild experimental conditions,
Colloid & Polymer Science, 2003, 281, 229 – 238. 2. Caponetti,
supramolecular clusters of urea, cyanamide, cobalt nitrate
E.; Chillura-Martino, D.; Ferrante, F.; Pedone, L.; Ruggirello,
and ytterbium nitrate confined in the core of sodium
A.; Turco Liveri, V.; Langmuir, 2003, 19, 4913 – 4922. 3.
bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles
Calandra, P.; Longo, A.; Ruggirello, A.; Turco Liveri, V.;
and suspended in an apolar organic solvent have been
Journal of Physical Chemistry B, 2004, 108, 8260 – 8268. 4.
obtained [1-5]. In any case, experimental results
Ceraulo, L.; Filizzola, F.; Longo, A.; Ruggirello, A.; Turco
emphasized that, due to confinement and interfacial
Liveri, V.; Colloid & Polymer Science, 2006, 284, 1085 – 1095.
effects, these clusters show physicochemical properties
5. Longo, A.; Ruggirello, A.; Turco Liveri, V.; Chemistry of
different from those in the bulk state or isolated
Materials, 2007, 19, 1127 – 1133.
molecules whereas, due to the increase of the amount of
hydrophilic compound confined in the micellar cores, the
structural properties of the reverse micellar aggregates
are more or less significantly affected. Moreover, a
P 3.11
comparison of the maximum attainable value of the
solubilizate-to-surfactant molar ratio in reverse micellar
solutions suggests that it critically depends on the nature
Investigation of the adsorption of PEG1500-12-
of solubilizate, surfactant and apolar solvent showing
acyloxystearate surfactants into phospholipids
frequently marked supersaturation effects.
bilayers:
Here
we
report
characterization
of
on
the
iron(III)
entrapment
chloride
and
clusters
An Ellipsometry and Cryo-TEM
study.
FT-IR
Mauro Vaccaroa,c, Christian von Corswantb, Olle
in
AOT/CCl4 micellar solutions as a function of the salt-to-
Södermanc.
surfactant molar ratio R at fixed surfactant concentration.
a
Interestingly, while the confinement of many water-
Dipartimento di Chimica, via Cinthia, 80126 Napoli,
soluble inorganic salts in AOT reverse micelles needs
mauro.vaccaro
Università
93
degli
Studi
di
@fkem1.lu.se;
Napoli
CSGI
Federico
–
II,
Consorzio
interuniversitario per lo sviluppo dei Sistemi a Grande
[1] McNamee, C., M. Nilsson, C. von Corswant, and O.
Interfase.
Söderman.
b
PEG1500-acyloxy-stearate Micelles and Liquid Crystalline
Sweden.
Phases. Langmuir. 21: 8146-8154.
AstraZeneca R&D Mölndal, SE 431 83 Mölndal,
2005.
Physicochemical
Characterization
of
c
Physical Chemistry 1, Lund University, Box 124, 22100
Lund, Sweden.
In this communication, we present a study of a new class
of surfactants denoted as PEG1500-12-acyloxystearate 1,
P 3.12
which has potential use as pharmaceutical solubilizers.
interesting
Characterisation of new gold catalysts supported
properties with regard to cell damage effects. PEG1500-
on mixed ceria-titania oxides for the water-gas
12-acyloxystearates with C14 to C16 acyloxy chains
shift and preferential CO oxidation reactions
These
amphiphilic
molecules
present
display little or no damage to red blood and intestinal
Floriana Vindignia, Maela Manzolia, Anna Chiorinoa,
cells, whereas the surfactants with shorter chains, from
Tatyana Tabakovab, Vasko Idakievb, Flora Boccuzzia
C8 to C12, exhibit a measurable damage. To understand
the
underlying
mechanism,
systematic
studies
a
Department of Chemistry IFM, University of Torino and
of
NIS Centre of Excellence, via P. Giuria 7, 10125 Torino,
adsorption properties of the surfactants into phospholipid
Italy. [email protected]
bilayers were carried out by the use of ellipsometry. The
b
measurements revealed that the kinetic for the adsorption
Institute of Catalysis, Bulgarian Academy of Sciences,
Acad. G. Bonchev str., bl. 11, 1113 Sofia, Bulgaria.
process varies considerably with respect to the length of
the acyloxy chain. The rate of incorporation of the
Introduction
surfactants in the lipid membrane becomes slower upon
increasing the length of the acyloxy chain. Cryo-TEM
Gold catalysts, due to their high catalytic activity,
images have confirmed the ellipsometry results, by
particularly in CO oxidation at low temperature [1], are
showing that the dissolution of the phospholipid bilayer is
promising candidates both for H2 production, through
slower for the surfactants of the series having longer
methanol decomposition and water gas shift (WGS)
chains.
reactions, and purification, through the preferential CO
oxidation (PROX). The nature of the support on which
gold is dispersed plays a crucial role in determining the
catalytic activity. When Au nanoparticles are supported
on ceria, the systems are very stable and exhibit a high
activity for the WGS reaction [2] over a wide temperature
range, at different space velocity and H2O/CO ratios [3].
We observed recently that the addition of ceria is
effective on the stability and on the activity of other
catalysts in WGS reaction [4]. A TEM, FTIR and UV-Vis
characterisation has been undertaken on new gold
catalysts supported on CeO2-TiO2 mixed oxides with
different ceria loadings (20% - AuCe0.2Ti0.8 and 50% AuCe0.5Ti0.5) to get an interpretation of the positive effect
of ceria and to test the ability in the PROX reaction. All
the catalysts were prepared by deposition-precipitation
Figure 1: Cryo-TEM image of DOPC vesicles incubated
with PEG1500-C18C12 for half hour.
method and subsequent calcination at 670 K, to generate
strong contact between the metal and the oxide support.
The effect on the gold dispersion and on the catalytic
94
activity of different calcining temperature of the supports
RT (dashed line), at decreasing pressures (fine lines), and under
before the deposition has also been investigated.
outgassing at RT (bold line).
Results and discussion
References
HRTEM measurements evidenced that the two oxides,
1. Haruta M.; Tsubota S.; Kobayashi T.; Kageyama H., Genet
ceria and titania, are easily recognizable (ceria appears
M.J.; Delmon J.; J. Catal, 1993, 114, 175-192
darker than titania) and that they do not give rise to a
2. Tabakova T.; Boccuzzi F.; Manzoli M., Andreeva D.; App.
solid solution or to a new mixed phase. The diffraction
Catal. A, 2003, 252, 385-397.
fringes show highly defective oxide phases in both cases.
3. Andreeva D.; Idakiev V.; Tabakova T.; Ilieva L.; Falaras P.;
Figure 1 shows the FTIR spectra of CO adsorbed at
Bourlinos A.; Travlos A.; Catal. Today, 2002, 72, 51-57.
room temperature on oxidized catalysts.
4. Boccuzzi F.; Chiorino A., Tabakova T.; Manzoli M.; Idakiev
V.; Vindigni F.; Catalysis: a key to a richer and cleaner society
In addition to the usual bands related to CO weakly
Proceedings of Europacat VII, 28 August-1 September 2005,
bonded to the metallic gold step sites and to the
Sofia, Bulgaria.
uncoordinated support cations, a new absorption band, at
5. Vindigni F.; Manzoli M.; Chiorino A.; Tabakova T.; Boccuzzi
2166 cm-1, is present. This band is completely irreversible
F.; J. Phys. Chem. B, 2006, 110, 23329-23336.
to the outgassing at room temperature, giving an evidence
6. Wu X., Senapati L., Nayak S.K., Selloni A., Hajaligol M., J.
of a strong bond between the CO and the involved
Chem. Phys., 2002, 117, 4010-4015.
adsorption sites [5]. On the basis of its frequency and its
behaviour it has been assigned to cationic gold clusters
[6] stabilized on the structural and/or electronic defects.
The activity in the PROX reaction in presence of CO, O2
and H2 has also been studied in situ by FTIR. CO2
P 3.13
production is very fast, and the large intensity of the
related band indicates a high activity also in the presence
Gas-phase photocatalytic reduction of NOx onto
of an excess of hydrogen.
immobilized colloidal TiO2 nanocrystals: a
Conclusions
preliminary study
The FTIR data have evidenced positive gold clusters,
P. Ielpo1, G. Lasorella2, R. Comparelli2, A. Panniello1, M.
Striccoli2, M. Caselli1, A. Agostiano1,2, M. L. Curri2
stabilized by the mixed oxide surface, where CO is
1
strongly bonded and remains adsorbed up to the
Dipartimento di Chimica, Università di Bari, Via
Orabona 4, 70126 Bari, Italy
temperatures useful in PROX for PEM fuel cells
2
applications.
CNR IPCF, sez. Bari, c/o Dip. Chimica, Università di
Bari,
Via
Orabona
4,
70126
Bari,
Italy;
[email protected]
Nanostructured materials have been increasingly
investigated in the recent years due either to the
fundamental interest in their physical and chemical
properties and to the numerous application in different
scientific and technological fields. The possibility of
performing a kinetic control of the dimensions by using
suitable synthetic techniques has allowed the use of such
nanomaterial in optoelectronics, energy photoconversion
and photocatalysis. In the case of nanosized material, the
Figure 1. FTIR spectra of AuCe0.5Ti0.5 (a) and AuCe0.2Ti0.8
atoms residing at the surface represents a not negligible
(b) oxidized at 673 K after the adsorption of 15 mbar of CO at
95
fraction of the total number of atoms, and this fact
nitrogen oxide (NO2). For this purpose a suitable
dramatically affects the free energy of the crystalline
apparatus has been designed and set up by using a
material, and makes size-dependent the NC chemical-
cylindrical photoreactor carrying an UV-vis lamp able to
physical properties.
illuminate the TiO2 NC immobilized onto spherical glass
The
photocatalytic
by
beads while the gas carrier (O2) containing NO2 has been
semiconductors under UV irradiation represent an
made flowing through the system, in order to perform the
appealing and promising method to scale up gas pollutant
catalytic reduction. The gas mix is then bubbled in an
remediation by means of low cost processes. In
absorbing solution, acting as a trap for the residual, not
particular, numerous studies have been carried out in the
reduced, nitrate the residual, not reduced, NO2.
field of heterogeneous catalysis by using immobilized
An ion chromatographic analytical procedure has been
catalysts. However a significant loss of performances has
then developed, validated and applied to quantify the
been
nitrate amount after the reduction cycle.
recorded
in
the
degradation
case
of
assisted
deposited
bulk
semiconductors due to the decreasing of the surface
active
area.
In
this
perspective
The proposed approach thus offer a valuable tool to
nanocrystalline
monitor the NO2 reduction yield of the gas phase
semiconductors could be able to minimize this drawback
catalytic process, and to perform a kinetic study which
thanks to their extremely high surface to volume ratio.
allows an evaluation the efficiency of the system, as a
For this purpose the deposition technique and the choice
function of different experimental parameters, such as
of a proper substrate play a very important role.
catalyst composition (colloidal TiO2 NCs vs TiO2 P25
Nanostructured semiconductors have been successfully
Degussa), deposition route, gas flow, etc.
employed in the removal of organic and inorganic
pollutants in gas phase by means of photocatalytic
Acknowlegment
techniques. In this work a possible application of the
This work has been partically supported by the
colloidal TiO2 nanocrystal (NC) photocatalytic process
Explorative Project PE_049 funded by Apulia Region.
has been investigated to perform a gas phase reduction of
96
97
SEZIONE
CHIMICA FISICA DEI MATERIALI
97
range 173-343K within two independent models based on
the analysis of 129Xe NMR signal intensities and isotropic
chemical shifts variations observed in variabletemperature experiments. Additionally, studying the
pronounced chemical shift anisotropy and line shapes as a
function of temperature made it possible extracting
information on the structure of xenon-cavity complex, on
the flexibility of the nanopores and on molecular-scale
details of sorption process. The presented procedure is
suggested as an express method that allows obtaining
quantitative
thermodynamic parameters and molecular level
peculiarities of sorption in microporous materials. This
method may be particularly suitable for the
characterization of soft materials, where the flexibility of
the framework that might lead to permanent structural
changes (aging) and/or phase transitions do not allow the
application of standard analyses such the acquisition of
adsorption isotherms.
P 4.1
Nuclear Magnetic Resonance of 129Xe used as a
probe for the characterization of void space in
crystalline
microporous
dipeptides:
thermodynamics and molecular details of
sorption.
Roberto Anedda,a Dmitriy V. Soldatov,b Igor L.
Moudrakovski,c Mariano Casua and John A. Ripmeesterc
a
Department of Chemical Sciences, University of
Cagliari, Monserrato (CA), Italy. [email protected]
b
Nikolaev Institute of Inorganic Chemistry, Russian
Academy of Sciences, Novosibirsk, Russia
c
Steacie Institute for Molecular Sciences, National
Research
Council,
Ottawa,
Canada,
[email protected]
The suitability of 129Xe NMR in characterizing voids
comprised within porous materials and/or biomolecules
has recently given to this technique a widespread
diffusion. Among the reasons for this popularity are the
chemical inertness of Xe and the remarkable sensitivity
of its NMR parameters (chemical shift, line shape,
relaxation rate) toward non-bonded local environment1.
A wealth of information has been extracted so far on a
number of very different systems both in solution and in
solid state: for instance, Xe NMR has been used for the
characterization of ligand binding sites in proteins, to
distinguish protein conformation changes and detecting
blood oxygenation level. Moreover, in the solid state, due
to the sensitivity of 129Xe NMR parameters, the size and
shape of pores within some crystalline and amorphous
materials and the dynamics of sorption process have been
investigated.
Despite a number of progresses have recently
significantly improved the technique, many questions
concerning the molecular interaction of xenon with the
host structures and on the correlation between 129Xe
NMR parameters and size/shape of cavities still remain
unanswered. Moreover, the scientific interest toward this
technique is amplified by the possible use of xenon in
clinical imaging, anesthesia and to generate isomorphous
heavy-atom derivatives in structure determination by
single-crystal XRD.
In order to deepen the understanding of the inclusion
process, we concentrate on model systems which allow a
systematic study on thermodynamics and molecular
details of sorption of xenon in solid porous materials and
xenon binding to proteins in solution. This presentation
summarizes latest achievements on 129Xe NMR
characterization of solid microporous materials.
129
Xe NMR has demonstrated its validity in
characterizing porous materials with large pores (d >
1nm)1, where xenon NMR parameters are mediated by
exchange processes. Moreover, previous calculations
have shown that the 129Xe chemical shift anisotropy
observed in many microporous materials is related to size
and shape of the cavities/channels where xenon atoms are
sorbed. We studied a series of eight microporous
dipeptides: Ala-Val (AV), Val-Ala (VA), Leu-Ser (LS),
Ala-Ile (AI), Val-Val (VV), Ile-Ala (IA), Ile-Val (IV),
Val-Ile (VI). The sorbents belong to the group of
biozeolites and are formed by helical self-assembly of Hbonded dipeptides to generate isolated 1D chiral
nanochannels in the final crystalline material2. The
sorption of xenon was characterized with solid-state
continuous-flow 129Xe NMR. The isosteric heat of
sorption (qst) and entropy factors were determined in the
Figure. Fragment of the crystal structure of VA
(hexagonal, space group P61) showing H-bonding helical
assembly of the dipeptide molecules surrounding the
channel: a view along the channel (left) and side view
(right).
1. Ratcliffe, C. I.; Annu. Rep. NMR Spectrosc., 1998, 36, 124 –
208. 2. Soldatov, D. V.; Moudrakovski, I. L.; Grachev, E. V.;
Ripmeester, J. A.; J. Am. Chem. Soc. , 2006, 128, 6737 – 6744.
P 4.2
SiOx and SiNx layers with improved barrier
effect and tribological properties
E. Angelini1, R. d’Agostino2, S. Grassini1, F.
Palumbo3, F. Rosalbino1
1
Department of Materials Science and Chemical
Engineering, Polytechnic of Turin, Turin, Italy
2
Department of Chemistry, University of Bari, Bari, Italy
3
Institute for Inorganic Metodologies and Plasmas, CNR,
Bari, Italy
SiOx coatings deposited by PECVD of organosilicons,
can improve the corrosion resistance of metals in
different aggressive environments. Silicon based
materials including more or less C, O, N and H show
high potential for corrosion protection essentially because
they are dense (low permeability to water and gases),
amorphous, chemically inert and show a low electrical
conductivity or can be insulator depending on their
composition. Moreover, the coating promotes no galvanic
98
In this contribution, the synthesis and the characterisation
of
photoluminescent
hybrid
organic-inorganic
mesoporous nanoparticles (NPs) are described. Highly
fluorescent organic dyes of the indocarbocyanines family,
namely IRIS 3, have been embedded within the pores of
MCM-411.
The host-guest interaction between the inorganic
framework and the organic dyes is extremely effective in
protecting the dye and enhancing its emitting
performances, with no structural modification of the
inorganic material.
The bulk material, obtained by impregnation of the
mesoporous host with dyes solution, was nano-sized by
sonication, preserving the features of both the organic
dye and the mesoporous structure. A complete physical
chemical characterization of the bulk material and the
NPs was performed by X-Ray Diffraction (XRD), High
Resolution
Transmission
Electron
Microscopy
(HRTEM),
UV-Vis
and
Photoluminescence
spectroscopy.
NPs spectra were recorded by analyzing NPs suspensions
at different pH values of phosphate buffer saline solutions
(pH=3.60; pH=5.50; pH=7.40; pH=9.00), corresponding
to the environment in different cellular compartments.
One of the application of this new material is in the field
of diagnostics and molecular imaging3, thus the biocompatibility and cytotoxicity of silica nanoparticles
were assessed in mastocytes-like RBL cells, using a
confocal microscope.
coupling deleterious to the uncoated metallic surface.
From the mechanical point of view, SiOx coatings are
know to be rather brittle, therefore, the substitution of
oxygen by nitrogen should allow to get higher improved
tribological properties keeping the insulating nature, that
is one of the parameters responsible for corrosion
protection.
In this study an investigation of the tribological and
electrochemical behavior of SiOx and SiNx thin films has
been undertaken. Moreover, the deposition of
multilayers, such as SiNx/SiOx or SiOx/SiNx/SiOx, as well
as of Ti/TiN/SiOx and Cr/CrN/SiOx has been
investigated, too.
SiOx and SiNx have been deposited on stainless steel and
aluminium alloys in an RF parallel-plate reactor starting
from different organosilicon precursors (HMDSO, TEOS,
HNDSN, etc.) in mixture with argon and/or oxygen, with
different plasma pre-treatments, performed in H2, O2 and
NH3 containing plasmas. Ti/TiN and Cr/CrN films have
been deposited by magnetron sputtering, using Ti and Cr
targets at 200°C, 3,0⋅10-2 Torr and input power ranging
from 150 to 300W; N2 and Ar gases were used as a
reactive source and a sputtering gas, respectively.
The chemical characterisation of coatings has been
carried out by means of X-Ray Photoelectron
Spectroscopy (XPS) and Infrared Spectroscopy (FT-IR).
The barrier effect properties of deposited films have been
assessed by means of Electrochemical Impedance
Spectroscopy in aerated 0.1 M NaCl solution at room
temperature. Impedance spectra have been recorded at the
open circuit potential by applying a sinusoidal signal of
10 mV amplitude in the frequency range 100 kHz -10
mHz. The experimental data interpreted on the basis of an
equivalent circuit model allow to obtain the charge
transfer resistance, Rct, and the coating capacitance, Cc,
which can be directly related to the protective properties
of the coatings.
The mechanical and tribological properties of mono and
multilayers has been assessed by means of Vickers
microhardness measurements and sliding wear resistance
test (pin-on-disc).
Morphological characterization of deposited films has
been performed, before and after the tribological and
electrochemical tests, by means of scanning electron
microscopy (SEM).
The tribological and electrochemical behaviour of the
coatings increases with the power density of the
discharge, and with the oxygen content of the feed gas.
When the deposition process is preceded by a proper
plasma treatment, which depends on the metal under
study, a marked increase of the protective properties is
detected.
Moreover, a marked increase of the barrier effect ,
without affecting their mechanical properties, has been
observed for Ti/TiN/SiOx and Cr/CrN/SiOx coated steel
in comparison to magnetron sputtered ones.
1.Gianotti, E.; Bertolino, C.A.; Caputo, G.; Coluccia, S.;
Microporous and Mesoporous Materials (submitted)
2. J.Bujdák, N.Iyi, T.Fujita, Colloids and Surfaces A, 2002, 207,
207-214.
3. Santra, S.; Liesenfeld, B.; Bertolino, C.A.; Dutta, D.; Cao, Z;
Tan, W.; Moudgil, B.M.; Mericle, R.A.; Journal of
Luminscence, 2006, 117, 75-82.
P 4.4
THERMAL
ANALYSIS
CHARACTERIZATION
OF
SOME
PROCESSES
RELATED
TO
DISPROPORTIONATION OF STANNOUS
OXIDE
Bonicelli M. G.a, Ceccaroni G.b, Gauzzi F c.,
Mariano G.
a
Dipartimento Ingegneria Chimica, Materiali, Ambiente,
Sapienza Università di Roma, Via del Castro
Laurenziano 7, 00161 Roma, Italy
b,c
Dipartimento di Scienze e Tecnologie Chimiche,
Università di Roma Torvergata,Via O.Raimondo, 00173
Roma, Italy
The disproportionation products of SnO are Sn and either
SnO2 or an intermediate oxide (IO) SnxO1+x depending on
the reaction temperature. A dispersion of Sn droplets into
the oxides results from this process. In a previous work
[1], the disproportionation products of pure SnO were
investigated by DSC with the aim of examining the
fusion and solidification behaviour of Sn droplets and the
catalytic nucleation of solid or liquid Sn on tin oxides. As
a subsequent development, SnO disproportionation has
been now carried out directly in the calorimeter: so that
heating and cooling rates we applied could vary over
larger intervals and their values were more exactly
P 4.3
Synthesis and characterization
organic/inorganic
mesoporous
nanoparticles
of hybrid
photoactive
Bertolino, C.A., Caputo, G., Gianotti, E.
Dipartimento di Chimica IFM e NIS Centre of
Excellence, Via P. Giuria 7, 10125 Torino,
[email protected]
99
measurable. It was also possible to obtain and analyze the
complete thermograms of disproportionation at various
temperatures. As far as the solidfication and fusion of
metallic Sn is concerned, the results are substantially in
agreement with those reported in [1]. Furthermore, the
deconvolution of the solidification thermograms of
metallic Sn in the presence of IO allows to estimate the
quantity of Sn that solidifies in correspondence of every
value of supercooling.
understanding of the field-effect transport properties
along with the conduction mechanisms of the above
films.
P 4.6
New advances in the
decomposition of H2SO4
[1] Bonicelli M.G. ;Ceccaroni G. ;Gauzzi F. ; Mariano G.:
Thermochimica Acta 2005 , 430, 95–99
high
temperature
S. Bruttia, L. Bencivennia, V. Barbarossab, G. De Mariaa
a
Dipartimento di Chimica, Università di Roma “La
Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
b
ENEA- Research Center “Casaccia” – 00060 S. M. Di
Galeria, Roma, Italy
P 4.5
The sulphur-iodine cycle is one of the most promising
thermochemical cycle for hydrogen production. Its
coupling with a solar energy primary source is a great
challenge to achieve an efficient and economically
competitive H2 production. Within this cycle the
decomposition of sulfuric acid plays a key role being this
process the most energy-demanding reaction step. Here a
combined computational and experimental study of the
decomposition at high temperature of H2SO4 to SO2 is
presented. From a computational point a view the role of
the hydrated gaseous coordination adducts of SO3(g) and
H2SO4(g) in the dissociation-decomposition process has
been evaluated. A first principles study of the gaseous
coordination complexes SO3(H2O)n (n=1-3) and
H2SO4(H2O)m (m=1-2) has been carried out deriving
equilibrium ground state structures, vibrational
frequencies and energetic stabilities. These results have
been used to derive the enthalpy of formation at 0 K and
the Gibbs energy functions of these molecules. A new
thermodynamic modeling of the decomposition of
H2SO4(g) has been therefore performed considering the
effect of temperature, pressure and initial composition of
the gas (hydration conditions).The experimental
investigation of the high temperature decomposition of
H2SO4 by using a standard electrical furnace and a
concentrated solar power furnace without catalysts or
using a Fe2O3-based catalyst was carried out. The
computational and experimental results obtained are
discussed together with the available literature.
Surface Chemistry Effects on the Early Growth
Stages of Pentacene Films from a Soluble
Precursor on Silicon-Based Materials
C. Musumeciζ,ξ, C. Cascioζ,ξ, A. Scandurraζ,ξ, G.F.
Indelliζ,ξ, C. BongiornoГ, S. Ravesiζ,Б and B. Pignataroζ, *
ζ
PLAST_ICs, Stradale Primosole 50, 95121, Catania
ξ
Superlab -Consorzio Catania Ricerche, Stradale
Primosole 50, 95121, Catania
Г
Istituto per la Microelectronica e Microsistemi (IMM),
Stradale Primosole 50, 95121, Catania
Б
ST-Microelectronics, Stradale Primosole 50, 95121,
Catania
*
Dipartimento di Chimica Fisica F. Accascina, V.le delle
Scienze – Parco D’Orleans II, 90128 Palermo,
[email protected]
To date among conjugated molecules pentacene
showed very promising transport properties which makes
it a good candidate for the build up of organic thin films
transistors (OTFT). Thin films of pentacene are usually
prepared by evaporation under vacuum since it is scarcely
soluble in organic solvent, especially in the green ones.
However, the developing of solution processes is in
several cases desirable as for the fabrication of low-cost
and large- scale plastics devices.
Here we show an innovative solution approach
which leads to the formation of pentacene thin films via a
retro Diels-Alder reaction by heating a thin film of a
soluble
pentacene
precursor
(13,6-N
Sulfinylacetamidopentacene) transferred on solid
interfaces through spin-coating. Our study is centred on
the early growth stages of pentacene crystals on both
hydrophilic
and
hexamethyldisilazane-treated
hydrophobic silicon-oxide materials. Such interfaces are
of relevant interest for OTFT as for instance the electron
mobility under field-effect has been demonstrated to
occur at the very first layers in direct contact with siliconbased dielectrics. In order to have a precise thickness
control of the films we employed for their preparation the
Langmuir-Blodgett method in addition to spin-coating.
By combining Atomic Force Microscopy, Transmission
Electron Microscopy and X-Ray Photoelectron
Spectroscopy, we found that the thermal treatment leads
to the complete conversion of the precursor and that the
early growth stages of pentacene crystals are strongly
influenced by the interface-chemistry. In particular
almost flat-lying molecules first nucleate in islands made
of molecules almost normal to the surface which then
develop in crystals up to some microns in diameter.
Compact and holed micro-crystals have been observed
respectively on the hydrophobic and hydrophilic surfaces.
The structural data provide important inside for the
P 4.7
Lithium Order-Disorder in Superionic LLTO:
Theory and Experiment
M. Catti
Dipartimento di Scienza dei Materiali, Università di
Milano Bicocca, 20125 Milano, [email protected]
LLTO (LixLa2/3-x/3 1/3-2x/3TiO3) is one of the materials
with the highest lithium ion electrical conductivity
(about 10-3 S cm-1 for x=0.3) at room temperature, of
interest as solid electrolyte or cathode in lithium
batteries.1 Structural studies of the x=0.3 term, performed
by TOF neutron powder diffraction on samples with
different thermal history, showed tetragonal perovskite
superstructures with ∼√2ap×√2ap×2ap unit-cells (ap ∼
3.87 Å for cubic perovskite).2,3 By Rietveld refinements
in the P4/nbm (unquenched) and I4/mcm (quenched
100
A. Convertino1, G. Leo1, M. Striccoli2, M. Tamborra3, C.
Sciancalepore3, M. L. Curri2
1 CNR ISMN, Via Salaria Km 29.300, 00016
Monterotondo St. (Roma), Italy
2 CNR IPCF, sez. Bari, c/o Dip. Chimica, Università di
Bari, Via Orabona 4, 70126 Bari, Italy
3 Dipartimento di Chimica, Università di Bari, Via
Orabona 4, 70126 Bari, Italy;
:
[email protected]
sample) space groups, the main findings were: anti-phase
octahedral tilting a0a0c-, partial La-Li ordering in two
independent (001) layers for the unquenched sample, and
lithium atoms located in two distinct disordered sites with
fourfold oxygen coordination within the A-type
dodecahedral cage of ABO3 perovskite. The short Li-Li'
distances account for the high ionic mobility and suggest
a mainly (001) two-dimensional mechanism of ion
hopping among Li sites.
The growing demand of our society to detect and
monitor gases and vapors for safety, health and
environmental issues requires a high degree of innovation
in sensor technology, which includes both the research
development of novel sensing materials and the
integration of original sensor architectures. Particular
attention has been devoted to polymers as sensing
materials for devices exploiting various transduction
signals, such as optical, mechanical, electrical and
thermal. Some recent results show that the presence of
inorganic nanoparticles (NPs) causes a further
modification of the sorption processes in a polymer
matrix [1]. Indeed the interaction between the NP surface
and the gas molecules can control the selectivity, rate and
efficiency, of molecule adsorption in the nanocomposite.
In addition, the high surface-to-volume ratio of NPs
increases the number of active sites for interaction with
the analytes. Hence, NP based polymer composites can
address an innovative generation of chemical sensors
combining the sensing abilities and the possibility of a
versatile tailoring of the physical properties of the NP
with the mechanical and/or optical responses related to
the gas sorption processes of the polymers. In this work
the sensing properties of Poly(methyl metacrylate)
(PMMA) based nanocomposite have been investigated as
a function of the shape (dot or rod), concentration and
surface ligands (oleic and phosphonic acid) of the
embedded TiO2 colloidal nanocrystals (NCs). Colloidal
chemical routes have been used to synthesize the TiO2
NCs with a high control on size, shape and crystal phase.
The surface chemistry of the NCs has been modified by
exploiting ligand exchange techniques.
Thin films of TiO2 NC-PMMA nanocomposite deposited
by spin coating on Si and glass substrates, have been
investigated by Vis-NIR spectrophotometry in presence
of organic vapors (acetone, ethanol). Films of PMMA
composites based on commercial TiO2 NCs have also
been prepared as comparison. The effects of the
surrounding vapors on the nanocomposite thin films have
been tested by reflectance measurements in the visible.
The vapor sensing behavior of the PMMA
nanocomposite have been estimated by measuring the
degree of swelling, ∆t/t, where t is the thickness of the
film and ∆t is the relative thickness variation, from the
reflectance spectra measured before and after the vapor
exposure [2]. Indeed, when the organic vapors are
adsorbed by the polymer host matrix, a reversible shift of
the fringe pattern has been observed in the reflectance
spectra for the nanocomposite films due to the reversible
film swelling. The overall results have indicated that, the
different shape of the embedded NCs and the presence of
the organic molecule layer coordinating the surface of the
TiO2 NCs appear to be critical in the sensing process, by
enhancing or inhibiting the swelling phenomenon of the
nanocomposite, and by modifying the response time of
the PMMA.
An ab initio periodic quantum-mechanical simulation
of possible locally ordered structures was then performed,
by use of the B3LYP hybrid functional and of an allelectron basis set of atomic orbitals (CRYSTAL06
code4).
The
compositions
Li0.5La0.5TiO3
and
Li0.3125La0.5625 0.125TiO3 were considered, with 4 to 16
formula-units of LLTO per primitive unit-cell, and with
symmetry lowered to monoclinic Pm. Several different
La-Li- ordering patterns within the (001) layers of Acages were devised. The structures were fully optimized
by energy minimization, so as to localize the preferred
lithium sites for each ordering scheme. Maps of the
electrostatic potential were also computed in ionized Lifree model structures, in order to study the electric field
acting on Li+ ions (cf. the figure). It was found that the
anti-phase octahedral tilt is reproduced only for layers
with mixed La-Li composition, and not for full La-Li
ordering in different layers. Further, the positions
adopted by lithium depend significantly on the locally
ordered environment, so that the two sites appearing in
the experimental average structure can be assigned to
specific ordered configurations on the basis of the
theoretical results obtained. The most populated Li site,
close to the O4 windows separating adjacent A cavities in
the layer, corresponds to La-poor local configurations,
and is actively involved in the ion migration process.
The other one, closer to the cage centre, is related to Larich local environments, and is a trapping location less
favourable to the transport mechanism.
1. Inaguma, Y.; Chen, L.; Itoh, M.; Nakamura, T.; Uchida, T.;
Ikuta, H.; Wakihara, M.; Solid State Commun,, 1993, 86, 689.
2. Sommariva, M.; Catti, M.; Chem. Mater,. 2006, 18, 2411. 3.
Catti, M.; Sommariva, M.; Ibberson, R.M.; J. Mater. Chem.,
2007, 17, 1300.
4. Dovesi, R.; Saunders, V.R.; Roetti, C.; Orlando, R.; ZicovichWilson, C.; Pascale, F.; Civalleri, B.; Doll, K.; Harrison, N.M.;
Bush, I.J.; D'Arco, Ph.; Llunell, M.; CRYSTAL06: User's
Manual; http://www.crystal.unito.it
P 4.8
Tuning of chemical and physical properties of
Poly(methyl metacrylate)- TiO2 nanocrystals
based nanocomposites for sensing applications
[1] A. Convertino et al. Adv. Mater. 13, 1103, (2003).
[2] A. Convertino et al. Sensors and Actuators B, (2007)
doi:10.1016/j.snb.2006.11.043.
101
Acknowlegment
This work was financially supported by the EC-funded
Project NOVOPOLY (Contract no. STRP 013619).
approaches, as it is the local environment around the two
PO4 groups.
The B3LYP calculations provide Mulliken net charges
which are close to the formal ionic charges showing the
ionic nature of the bioglass, whereas the large band gap
of 6.5 eV shows its strong insulating character.
As for vibration frequencies, in spite of great complexity
due to the large number of active modes, a good
agreement with experimental data was found, confirming
the reliability of the present model. Spectroscopic data
were compared also with simulated vibrational spectra of
pure amorphous silica, to highlight the role of phosphorus
and network modifiers cations.
The present attempt is the starting point of a more general
multiscale approach in which molecular mechanics
calculations will provide initial structures for ab-initio
simulation. This latter, in turn, will provide electronic
features of complex materials and can also be used to
refine, in a fully self consistent way, the force field
parameters derived empirically. Present DFT functionals
(hybrid ones in particular) have been proved excellent
tools for the simulation of static and dynamic properties
of silica-based materials.
P 4.9
A computational multiscale approach to the
modelling of 45S5 Bioglass®
M. Cornoa, A. Pedoneb, B. Civalleria, M.C. Menzianib
and P. Ugliengoa
a
Dipartimento di Chimica IFM Università di Torino, via
P. Giuria 7, 10125 Torino, [email protected]
b
Dipartimento di Chimica Università di Modena e Reggio
Emilia, via G. Campi 183, 41100 Modena
The Hench Bioglass® 45S5 of 48.1% SiO2, 25.9% CaO,
22.2% Na2O and 3.7% P2O5 composition is of great
interest in medical applications since in the presence of
body fluids, and depending upon the rate of ion release
and resorption, it creates chemical gradients which
promote the formation of a layer of biologically active
bone-like hydroxyapatite at the implantation interface.
Osteoblasts can preferentially proliferate on the apatite
layer, and differentiate to form new bone that binds
strongly to the implant surface.
Its simulation has been undertaken in a multiscale
approach in which molecular dynamics simulations based
on classical force fields have been carried out on a unit
cell containing 78 atoms with Na12Ca7P2Si13O44
composition and P1 symmetry. Molecular mechanics
minimization was then run on a representative quenched
structure, to relax fully the system which is subsequently
passed to the CRYSTAL06 code as a starting structure to
perform a full ab-initio periodic geometry relaxation
using the hybrid B3LYP functional with Gaussian basis
sets of double-ζ quality. The hybrid B3LYP has been
chosen because it has recently proved to be very
successful in the treatment of complex silicate crystals.
The full IR and RAMAN spectra of the Bioglass® have
been computed ab-initio and compared to experimental
results.
Some important points can be highlighted from the
comparison between the molecular mechanics and
B3LYP optimized structures (Figure 1) of the Bioglass
45S5.
P 4.10
Structural and chemical properties of the
hydroxyapatite surface. A computational ab
initio and a microcalorimetric/IR spectroscopic
characterization
M. Cornoa, L. Bertinettia, V. Bolisb, C. Buscob, G.
Martraa and P. Ugliengoa
a
Dipartimento di Chimica IFM Università di Torino, via
P. Giuria 7, 10125 Torino, [email protected]
b
Dipartimento DiSCAFF Università del Piemonte
Orientale “A. Avogadro”, via Bovio 6, 28100 Novara
Bioactive glasses, when implanted in the body or simply
immersed in simulated body fluids (SBF), develop a
biologically active hydroxyapatite (HA) layer which in
turn does promote the bone-tissue formation. In fact
hydroxyapatite, which exhibits strong similarities to the
mineral phase of the mammalian bones and teeth, does
play a key role during the bioactive glasses integration
processes, in that it facilitates adhesion and subsequent
proliferation of the osteocytes, so allowing the damaged
bone tissues to be repaired. The first step of these
processes is the adsorption of biomolecules at the active
surface of HA. Therefore, studies aimed at quantitatively
describing the structural and chemical properties of the
HA surface are of greatest interest, in the attempt to
elucidate at nano-level the interfacial processes involved
in the biological fixation of inorganic materials to the
living tissues.
In the present study, ab initio methods and
experimental techniques have been used to characterize
the adsorption features of HA surfaces using H2O and
CO as molecular probes. Periodic ab initio B3LYP
calculations using CRYSTAL06 code have run to
characterize the (001) and (010) bare surfaces for both
hexagonal and monoclinic HA phases. On the
geometrically relaxed surfaces the adsorption of H2O and
CO has been simulated, from low to high coverage.
Energies of adsorption and the vibrational features of
H2O and CO have been computed as a function of
coverage and compared with the corresponding
microcalorimetric data and infrared spectra.
Figure 1: view along the c axis of the B3LYP Hench
45S5 bioglass optimised unit cell
B3LYP optimized structures show a slightly higher
density than the one computed with the molecular
mechanics approach, this latter being also in good
agreement with the experimental one. This is due to a
known weakness of many GGA and hybrid functionals
which overestimate the Si-O bonds and underestimate the
Si-O-Si and Si-O-P angles, respectively. Ca and Na
distributions are in very good agreement between the two
102
a
The main conclusions from the simulations are that both
H2O and CO adsorb on the exposed Ca2+ ions which are
characterized by rather strong local electric fields,
although not strong enough to dissociate H2O. The (001)
surface is more active than (010) when considering CO as
a probe.
H2O adsorption studies on the (010) are, at the moment,
still in progress. For the CO case, comparison between
the computed and the measured CO stretching
frequencies confirms that the exposed Ca2+ ions behave
as a Lewis acidic sites, in that bathochromic shifts have
been measured and computed. Microcalorimetric data for
the CO adsorption are still in progress, whereas the RT
adsorption of H2O on a nanosized HA specimen has
already been investigated.
In Figure 1 the heat of adsorption of H2O vapour is
reported as a function of the adsorbed amount. The
energy of interaction is quite high not only in the early
stage of the process but also at high coverage
(correspondent to the formation of a second shell of
coordinated H2O). The interaction energies computed at
B3LYP level are in fair agreement with the experimental
heats, confirming that the interaction (which is also
partially irreversible upon evacuation) is quite strong (see
Figure 1).
It is suggested that the strong, but still molecularly
coordinated H2O on the cus Ca2+ cations at the HA
surface has likely an implication in the adsorption of
proteins at the hydrated layer interface. Indeed, if reactive
Ca-OH groups were formed at the surface upon contact
with H2O, denaturation of proteins would occur
hampering cells adhesion.
CNR-IPCF Sede Bari, c/o Dip. Chimica – Via Orabona
4, Bari, I-70126, Italy; [email protected]
b
Università di Bari – Dip. Chimica, Via Orabona 4,
Bari, I-70126, Italy
c
Laboratories for Supramolecular Chemistry and
Technology MESA+ Institute for Nanotechnology,
University of Twente P.O. Box 217, 7500AE, Enschede
(TheNetherlands)
The functionalization of colloidal nanocrystals (NCs) is a
fundamental goal to exploit NCs as building-blocks for
the realization of ordered architectures in 2 and 3
dimensions.1
A plethora of approaches have been exploited in
assembling nanoparticles, such as fluid-aligned,
surfactants-interacted,
DNA-directed,
electrostaticinteraction
oriented,
and
recognition-mediated
organization.2
In this work, luminescent semiconductor NCs of different
chemical composition (CdS and CdSe@ZnS) have been
synthesized by colloidal chemistry routes and
functionalized by means of silanol groups. The
silanization procedure, typically used to make watersoluble and biocompatible NCs,3 consist of the growth of
a thin silica shell on the NCs surface allowing to
introduce suitable functional groups on the surface of the
silica network. Herein, we modified the silanization
approach to confer tailored functionality (amine, thiol,
and phosphonate moieties) to CdS and CdSe@ZnS NCs.
The obtained water soluble silanized NCs have been
extensively investigated by means of optical (UV-Vis,
PL, PL time-resolved, FTIR), structural (HRTEM) and
electrophoretic techniques.
The functional groups of silanized NCs have been
exploited to direct the electrostatic interaction driven
assembly of such luminescent NCs onto patterned silicon
substrates functionalized with amino-alkyl SAM
(5x3µm)4. The obtained assembly has been investigated
by means of microscopic techniques (fluorescence
microscopy and AFM) which confirm the selective
binding of the silanized NCs to the SAM molecules.
Acknowledgment. The partial support of the EC-funded
project NaPa (Contract no. NMP4-CT-2003-500120) is
gratefully acknowledged. The content of this work is the
sole responsibility of the authors.
1. Shipway, A.N.; Katz, E.; Willner, I; ChemPhysChem. 2000,
1, 18-52 2. Depalo, N.; Comparelli, R.; Striccoli, M.; Curri,
M.L.; Fini, P.; Giotta, L.; Agostano, A.; Journal of Physical
Chemistry B 2006,110,17388-17399 and reference therein 3.
Gerion, D.; Pinaud, F.; Williams, S. C.; Parak, W.
J.; Zanchet, D.; Weiss, S.; Alivisatos, A.; Journal of
Physical Chemistry B; 2001, 105, 8861-8871. 4.
Maury, P; Escalante, M; Reinhoud, D. N.; Huskens, J; Advanced
Materials, 2005, 17, 2718-2723.
Figure 1: differential heats and B3LYP energies of
adsorption of H2O vs coverage on nanosized HA
In conclusion, the joint use of experimental and
computational approaches has been found extremely
fruitful to elucidate the molecular events which are
responsible of the adsorption processes occurring at the
HA surfaces.
P 4.12
P 4.11
Physical
properties
of
the
magnetic
superconductor Ru – 1222 obtained from Ru–
1212 and Ce0.6Gd0.4O1.8 powders
Tailored functionalization of luminescent
colloidal nanocrystals for selective 2/3D
assembly
G. A. Costa a, C. Artini a, M. M. Carnasciali b, R. Masini c
d
and A. Ubaldini
a
INFM and DCCI, Via Dodecaneso 31, 16146 Genova
INSTM and DCCI, Via Dodecaneso 31, 16146 Genova
c
CNR-IMEM, Via Dodecaneso 33, 16146 Genova
M.Corricellia, R. Comparellia, N. Depalo,b M. Striccolia,
V. Saadhu,c J. Huskens,c M.L. Curria
b
103
NIMS, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
The ruthenocuprates RuSr2RECu2O8 (Ru – 1212) and
RuSr2(RE1-xCex)2Cu2O10 (Ru – 1222) are very attractive
compounds, as they present at the same moment
superconductivity and many complex magnetic orderings
[1, 2]. While, on one hand, the synthesis of these
materials is apparently simple, the reported values of the
transition temperatures are critically dependent on the
sample preparation conditions [3]. Classical solid state
route requires a preliminary calcination of the precursors
in argon and then many subsequent annealings in oxygen.
Previous results have shown that at the end of the first
step in argon the system is formed in the case of Ru –
1212 by RuSr2GdO6 and Cu2O, and in the case of Ru –
1222, in addition to these, also by (RE1-xCex)O2-x/2. In
flowing oxygen these phases react to form the
ruthenocuprate [4]. For the Ru – 1222 the presence of
three different phases makes the reaction more complex.
Actually, it is possible to detect the presence of Ru –
1212 in samples of Ru – 1222 prepared at low
temperature.
In this work, polycrystalline Ru – 1222 synthesised by a
different route was studied with the aim of preparing
samples with higher degree of purity. This compound
was obtained from the reaction between Ru – 1212 and
Gd0.4Ce0.6O1.8 previously prepared. The former was
synthesised following the classical procedure [5] and the
latter using a co-precipitation method [6]. They were
mixed and calcined in flowing oxygen in several
subsequent steps.
The structural, electrical, magnetic and spectroscopic
characterisations of the so formed RuSr2Gd1.4Ce0.6Cu2O10
are reported.
photodegradation of a wide number of organic
compounds can be found in literature. Since there is
almost unanimous agreement that the photocatalytic
reactions occur at the surface of the TiO2 particles,
specific adsorption of ions can affect the performance of
the system. For instance, the influence of several anions,
such as halides, on the photocatalytic processes involving
some target organic molecules were considered. In
particular, the beneficial effect of fluorination of TiO2
P25 on the photocatalytic production of H2O2, during
phenol degradation was studied by Minero and coworkers
[1,2]. Tough such influence was well assessed, no detail
information about the surface states of fluorinated titania
was obtained. Moreover, studies on different kind of
commercial titania powders, namely Merck and P25
Degussa, have highlighted remarkable differences in their
surface structure [3].
Based on these reasons, this work is aimed to compare
the effect of fluorination on both TiO2 Merck and P25
powders. Different levels of fluorination were attained
by OH-surf/F- exchange at various pH (Figure 1).
2.0E-06
1.8E-06
1.5E-06
F - ads , m ol m -2
d
1.3E-06
1.0E-06
7.5E-07
5.0E-07
2.5E-07
0.0E+00
2
3
4
5
6
7
8
pH
Figure 1: Amount of F- adsorbed on TiO2 P25 (10 g L-1)
as a function of pH and of the concentration of HF in the
exchange solution: ({) HF 1.0 mM, (∆) HF 0.5 mM
1. Jorgensen, J. D.; Chmaissem, O.; Shaked, H.; Short, S.;
Klamut, P.W.; Dabrowski, B.; Tallon, J.L.; Physical Review B
2001 63 054440-1/5. 2. Butera, A.; Fainstein, A.; Winkler, E.;
Tallon, J.L.; Physical Review B 2001 63 0544420-1/5. 3. Artini,
C.; Cimberle, M. R.; Costa, G.A.; Carnasciali, M.M.; Ferretti,
M.; Masini, R.; Ruthenate and rutheno-cuprate materials: theory
and experiments, Springer Verlag LNP series, ed.: C. Noce, A.
Vecchione, M. Cuoco, A. Romano, 2002 603 222-238. 4. Artini,
C.; Ubaldini, A.; Firpo, F.; Carnasciali, M.M.; Bruzzone, G.;
Costa, G.A.; Masini, R.; Cimberle, M.R.; Tropeano, M.; Applied
Superconductivity 2003, Proceedings of the 6th European
Conference on Applied Superconductivity, Sorrento, 1418/9/2003 2004 1167-1173. 5. Artini, C.; Carnasciali, M.M.;
Costa, G.A.; Ferretti, M.; Cimberle, M.R.; Putti, M.; Masini, R.;
Physica C, 2002 377 431-436 .6. Mele, P.; Artini, C.; Masini, R.;
Costa, G.A.; Hu, A.; Chikumoto, N.; Murakami, M.; Physica C
2003 391 49-54
In the case of the P25, significant differences were
observed for the bare and fluorinated TiO2 powders.
Conversely, TiO2 Merck in both the bare and fluorinated
forms exhibited similar performances in the
photoproduction of H2O2, that, in turn, appeared close to
the behaviour of TiO2 P25 with a higher amount of
fluoride.
The bare TiO2 and the derived fluorinated samples were
studied by infrared spectroscopy: i) after outgassing at
room temperature, when the titania surface is still retains
hydroxyl groups and water molecules coordinated to
surface cations, and ii) after outgassing at 150° C, when
water from the extended faces is usually removed [3]. As
for the powders simply outgassed at r.t., the IR spectrum
of the bare sample showed a series of components in the
3800–3600 cm−1 range, due to the stretching mode (νOH)
of different types of free hydroxyl groups, and an intense
and broad absorption in the 3600–3200 cm−1 range, due
to hydroxyls and water molecules bonded via hydrogen
bond. In this region a maximum at 3418 can be observed,
arising from the superposition of the νOH mode of
bonded hydroxyl groups and of the symmetric and
antisymmetric νOH modes of molecular water
coordinated to four coordinated Ti4+ions, typically
exposed on (1 1 0) faces. The variety of components in
the 3800–3600 cm−1 region is consistent with a large
heterogeneity of hydroxyl groups, arising from the
different kinds of planes exposed at the surface of the
TiO2 P25 microcrystals and from the presence of sites in
defect position [3]. At lower wavenumbers, the spectrum
is characterised by a main band located at ca. 1630 cm-1,
due to the bending of water molecules. In the case of the
samples containing different amount of fluoride, a higher
P 4.13
Fluorination of TiO2: effects on surface hydroxyl
groups and photoreactivity
M.G. Fagaa,c, M. Minellab, V. Maurinob, G. Martraa, C.
Minero b, E. Pelizzettib, S. Colucciaa
a
Dipartimento di Chimica IFM e Centro di Eccellenza
NIS, Università di Torino, Via Pietro Giuria 7, 10125
Torino, Italy.
b
Dipartimento di Chimica Analitica e Centro di
Eccellenza NIS, Università di Torino, Via Pietro Giuria
5, 10125 Torino, Italy.
c
CNR-ISTEC, Strada delle Cacce 73, 10135 Torino
Titanium oxide plays and important role in the field of
photocatalysis. Several studies related to the
104
Absorbance (a.u.)
relative intensity of the δH2O mode, proportional to the
amount of F-, was found, indicating and increased
hydrophylicity of the materials. Some slight difference in
the spectral pattern of isolated hydroxyls was also
observed. Even after outgassing at 150 °C the fluorinated
powders still exhibited a higher hydrophilicity, retaining
higher amount of adsorbed water. Furthermore, the
spectral pattern related to isolated hydroxyl groups
underwent significant changes (Figure 2). In the case of
the bare sample, four main partially resolved components
at 3730, 3690, 3670 and 3650 cm-1. Passing to the sample
with a low amount of fluoride (prepared at pH = 6), the
peak located at 3670 cm-1 became the dominant feature,
while the 3690 cm-1 one almost disappeared and the
3730 cm-1 component appeared stronghly decreased in
intensity. In the case of the titania with a higher level of
fluorination, an even more simplified νOH pattern was
obtained, characterized a main component at 3670 cm-1,
with an unresolved shoulder at 3650 cm-1. Interestingly,
this pattern appeared quite similar to that of the bare
TiO2 Merck, that exhibited similar photoproduction of
H2O2.
3670
3650
Eleonora Garbin, Elisabetta Collini, Camilla Ferrante,
Renato Bozio
Dipartimento di Scienze Chimiche e UdR INSTM di
Padova, Università di Padova, Via Marzolo 1, I-35131
Padova, Italy
Ultrafast Transient Absorption (TA) experiments
performed
on
tetrathiafulvalene
perchlorate
(TTF+·ClO4¯) in solution and polymer films are
presented.
In DMSO solution and in polymer matrices the TTF+·
radical forms dimers, characterized by a first excited
singlet state with a strong charge transfer (CT) character,
falling at 770 nm.1,2 In the TA experiments the pump
beam is resonant with the CT transition of the dimer
while the probe is tuned between 675 nm and 1100 nm.
The transient decay curves show a double exponential
behavior with characteristic time constants of 220 ± 90 fs
and 3.0 ± 1.3 ps. When the probe wavelength is smaller
than 875 nm, both components appear as bleaching
features, while when it is larger than 875 nm, the first
component is still a bleaching, and the longer decay
appears as photo-induced absorption (PIA). We attribute
the 220 fs bleaching feature to a spectral diffusion effect,
while the 3.0 ps component is attributed to the lifetime of
the lowest CT state. The latter component appears as a
bleaching when the ground state absorption is stronger
than the excited state one (under 875 nm), and it turns
into PIA when the opposite happens (above 875 nm).
In acetonitrile solution, instead, only the monomer form
is present. TA experiments are performed with the pump
beam set at 403 nm while the probe beam is tuned in the
425-625 nm range. The transient decay curves show a
double exponential behavior with characteristic time
constants of 1.4 ± 0.7 ps and 21 ± 7 ps.
0.25
TiO2 fluorinated at pH 3
νCHx
(impurities)
TiO2 fluorinated at pH 6
bare TiO2
3690
3730
3800 3600 3400 3200 3000 2800
-1
wavenumber (cm )
1. Torrance, J. B.; Scott, B. A.; Welber, B.; Kaufman, F. B.;
Seiden, P. E.; Physical Review B, 1979, 19, 730
2. R. Bozio and C. Pecile, in Spectroscopy of Advanced
Materials, Eds. R.J.H. Clark and R.E. Hester, 1991, J. Wiley &
Sons, Chichester
Figure 2: IR spectra, in the νOH region, of TiO2 P25 in
the bare form and after fluorination at pH= 6 and pH=3.
All samples were outgassed at 150 °C.
The results clearly put in evidence a dependence of the
surface hydrophilicity on the fluorination degree for the
P25 powder.
Furthermore, the evolution of the spectral pattern in the
hydroxyls stretching region indicated that fluoride ions
replaced hydroxyls present at the surface of the TiO2 P25
in peculiar positions only. From a morphological point of
view, HR-TEM images of TiO2 P25 evidenced the
presence of relevant amount of corner, edge and kink
surface terminations, absent in the case of TiO2 Merck.
The similarity of the νOH pattern of the TiO2 P25 with a
higher fluoride content with that of the bare TiO2 Merck
makes then allowance to propose that such “peculiar
position” are coordinatively defective surface sites.
P 4.15
Squaraine dyes as powerful nonlinear absorbers
in the NIR region
Elisabetta Collini1, Ilaria Fortunati1, Luca Ciaffoni1,
Camilla Ferrante1, Renato Bozio1, Luca Beverina2,
Alessandro Abbotto2, Giorgio A. Pagani2
1Dipartimento di Scienze Chimiche e UdR INSTM di
Padova, Università di Padova, Via Marzolo 1, I-35131
Padova, Italy
2 Dipartimento di Scienze dei Materiali e Unità di
Ricerca INSTM, Università di Milano-Bicocca, Via Cozzi
53, I-125 Milano, Italy
References
1. Minero, C.; Mariella, G.; Maurino, V.; Pelizzetti, E.;
Langmuir, 2000, 6, 2632-2641.
2. Minero, C.; Mariella, G.; Maurino, V.; Vione, D.; Pelizzetti,
E.; Langmuir, 2000, 16, 8964-8972.
3. Martra, G.; Applied Catalysis A: General, 200, 2000, 275-285
and reference therein
Squaraine dyes have always attracted attention for their
peculiar electronic structure and for the possibility to
exploit them as sensitive materials in electro-photography
and as singlet oxygen sensitizers. 1,2 Furthermore these
dyes are capable to give rise to various kind of
aggregates, depending on the solvent or solid state
matrix in which they are embedded.3
Very recently some of us have also shown that squaraine
derivatives, suitably substituted with electronwithdrawing or electron-donating groups, are endowed
P 4.14
Transient Absorption properties of
monomer and dimer of TTF radical cation
the
105
we present an investigation of the non-linear optical
(NLO) properties of two octupolar chromophores:
[Zn(4,4’-bis(dibutylaminostyryl)-[2,2’]-bipyridine)3]2+
and [Zn(4,4'-bis((E)-2-(N-(TEG)pyrrol-2-yl)vinyl)-[2,2']bipyridine)3]2+ with Zn(II) as the coordination center,
using two-photon induced fluorescence technique (TPF)
in fs-pulse temporal regime. Compared to the free
ligands, our results do not show a net increase in the twophoton absorption (TPA) cross-section for the octupolar
complexes, once normalized to the ligand unit. This result
is in partial disagreement with theoretical studies
investigating the former complex where a significant
increase of the TPA cross-section is predicted.5,6
with extremely high two photon absorption (TPA)
coefficients in the NIR region.4
In this communication we will present the linear and non
linear optical characterization of a class of highly
conjugated pyrrole containing squaraine dyes in solution.
In particular the linear absorption and resonance Raman
spectra will be presented, together with the TPA spectra.
The latter have been recorded with the Z-scan technique,
employing ~ 150 fs long pulses in the wavelength range
750-1100 nm, as well as the two-photon induced
fluorescence technique, exciting the samples with an
ultrafast laser source delivering 150 fs long pulses in the
750-900 nm range. The results show that some of these
dyes are characterized by TPA cross section of the order
of thousands of Göppert-Mayer (1GM = 1×10-50 cm4
photon s-1 molecule-1).
Singlet oxygen production of these molecular systems
has also been investigated through luminescence
experiments detecting the 1270 nm emission of singlet
oxygen.
1. Sénéchal, K.; Maury, O.; Le Bozec, H.; Ledoux I.; and Zyss,
J.; J. Am. Chem. Soc. , 2002, 124, 4560.
2. Maury O.; and Le Bozec, H.; Acc. Chem. Res., 2005, 38, 691.
3. Zheng, Q.; He G.S.; and Prasad, P.N.; J. Mater. Chem., 2005,
15, 579.
4. Coe, B. J.; Samoc, M.; Samoc, A.; Zhu, L.; Yi Y.; and Shuai,
A. Z.; J. Phys. Chem. A, 2007, 111, 472.
5. Liu, X. J.; Feng, J. K.; Ren, A. M.; Cheng, H.; and Zhou, X.;
J. Chem. Phys., 2004, 120, 11493.
6. Zhang, X-B; Feng, J-K; Ren, A-M; J. Chem. Phys. A, 2007,
111, 1328.
1. Law, K.Y.; Chem. Rev., 1993, 93, 499
2. R. Bonnet, “Chemical aspects of Photodynamic Therapy”,
Gordon and Breach, 2000.
3. Chen, H.; Farahat, M. S.; Law, K. Y.; Whitten, D. G.; J. Am.
Chem. Soc., 1996, 18, 2584.
4. a) Beverina, L.; Abbotto, A.; Landenna, M.; Cerminara, M.;
Tubino, R.; Meinardi, F.; Bradamante, S.; Pagani, G.A.; Org.
Lett. 2005, 7(19), 4257-4260. b) Chung, S-J; Zheng, S.; Odani,
T.; Beverina, L.; Fu, J.; Padilha, L.A.; Biesso, A.; Hales, J.M.;
Zhan, X.; Schmidt, K.; Ye, A.; Zojer, E.; Barlow, S.; Hagan, D.;
Van Stryland, E.; Yi, Y.; Shuai, Z.; Pagani, G.A.; Bredas, J-L;
Perry, J. W.; Marder, S.R.; J. Am. Chem. Soc. , 2006, 128(45),
14444.
P 4.17
EFFECT OF GRAIN SIZE ON THE
MAGNETIC PROPERTIES OF La1-xCaxMnO3
MANGANITES NANOPARTICLES
P 4.16
C. Castellano1, M.R. Cimberle2, M. Ferretti1,3, A.
Martinelli1 and R. Masini2
1
LAMIA-INFM-CNR, Corso Perrone 24, 16152 Genova,
Italy
2
CNR-IMEM sezione di Genova c/o Dipartimento di
Fisica, Via Dodecaneso 33, 16146 Genova, Italy
3
Dipartimento di Chimica e Chimica Industriale,
Universita’ di Genova, Via Dodecaneso 31, 16146
Genova, Italy
TPA Absorption properties of octupolar metal
complexes
Simone Mazzucato 1, Ilaria Fortunati 1, Sara Scolaro 1,
Michele Zerbetto 1, Camilla Ferrante 1, Raffaella
Signorini 1, Danilo Pedron 1, Renato Bozio 1, Danika
Locatelli 2, Stefania Righetto 2, Dominique Roberto 2,
Renato Ugo 2, Alessandro Abbotto 3, Graziano Archetti 3,
Luca Beverina 3, Sergio Ghezzi 3
1
Dipartimento di Scienze Chimiche e UdR INSTM di
Padova, Università di Padova, Via Marzolo 1, I-35131
Padova, Italy
2
Dipartimento di Chimica Inorganica, Metallorganica e
Analitica and Centro di Eccellenza CIMAINA
dell’Università di Milano, UdR INSTM di Milano, via
Venezian 21, 20133 Milano, Italy.
3
Dipartimento di Scienze dei Materiali e Unità di
Ricerca INSTM, Università di Milano-Bicocca, Via Cozzi
53, I-125 Milano, Italy
Manganites La1-xCaxMnO3 are objects of an intense study
due to the complexity of their phase diagram (1). They
present, as a function of the doping x, magnetoconductive phase transitions, charge ordering (CO) of the
ions Mn3+/Mn4+ in sub-lattices and above all the so-called
colossal negative magnetoresistance also greater than 90
%. Only in the last years, beside theoretical models based
on the double exchange mechanism and on a strong
electron-phonon coupling as a Jahn-Teller polaron at high
temperature (T > TCurie ≈ 270 K), several evidences of
nanophase inhomogeneities at low T between a metallicferromagnetic component and an insulating Jahn-Teller
distorted one have been obtained for 0.2<x<0.5 (2-4).
The nature of this last insulating phase is still uncertain
but it is probably a CO component with a very low
coherence length and then not visible by diffraction or
conventional spectroscopy measurements (5). Then
recent developments of research have discovered new
aspects that insert the study of manganites in the context
of natural or self-assembled nanostructured materials and
not only in that of strongly correlated electron systems
(2).
The second order non linear response of multipolar metal
coordination compounds has been thoroughly
investigated in recent time 1,2 with the aim to incorporate
them in solid state matrices as active materials for
photonic devices. Only in the last couple of years the
third order non linear response of these complexes has
also started to be investigated, since they appear to be
promising candidates as multiphoton absorber in optical
switches and optical limiting devices; a large multiphoton
absorption cross section, coupled with a good
luminescence quantum yield, is also required in the field
of bio-imaging and up-converted lasing. 3,4 In this work
106
The mesoscopic and nanoscopic phase texture of
manganites allows to continue to miniaturize transistors
and electronic components useful for computer
engineering and spintronics applications, in particular
providing a potential alternative to the conventional Si
lithography top-down and bottom-up syntheses
techniques. This result, which goes beyond silicon
limitations, should be due to the possibility to alter the
magnetic and electronic structure of a manganite on a
nanoscopic scale (6,7).
For these reasons we have investigated the effect of
nanometric grain size on magnetic and electronic
properties of different La1-xCaxMnO3 nanocrystalline
samples obtained by two different techniques: highenergy ball milling and sol-gel route (Pechini process,
ref. 8).
In the first case the samples were prepared by a
conventional solid state reaction at high temperature and
high-energy ball milling was subsequently carried out for
different time.
In the second case, after calcinations of the dried gel, the
oxides were submitted to various thermal treatments to
obtain different grain sizes in a range of 10-30 nm.
All samples have been characterized by X-ray powder
diffraction (XRD) and High Resolution Transmission
Electron Microscopy (HRTEM). Electric properties have
been investigated by impedance spectroscopy
measurements (EIS) carried out as a function of
temperature and composition of the nanostructured
manganites. Magnetic properties have been investigated
by means of dc and ac magnetic measurements in the
temperature range 5-350 K.
We evidence that the grain of our samples reach
dimensions also much below the values already reported
in literature (about 10 nm instead of 15-20 nm (9)).
Therefore we suppose that our smaller grain powders can
give rise to a superparamagnetic phase when their sizes
are lower than a critical threshold (9). This result is due to
the gradual reduction of the grain core size respect to the
non-magnetic outer grain shell and is strongly related to
the spin-polarized transport of conduction electrons at the
grain boundaries. The ac magnetic measurements (Fig. 1)
seem to confirm this hypothesis evidencing a broadening
and relevant shift of the ferromagnetic transition only in
powders of smaller grain dimensions, probably due to
such superparamagnetic disorder.
Moreover we observe a similar dc magnetic behaviour in
Mn-substituted samples (e.g. La0.25Ca0.75Mn0.92Cr0.08O3,
see Fig. 2). In these samples we induce chemical defects
determining a random impurity effect and therefore a
disordered Jahn-Teller distortion (5). In the framework of
manganites nanophase inhomogeneity this effect favours
the appearance of ferromagnetic nano-clusters in the long
range insulating matrix, whose magnetic behaviour is
very similar to that of a superparamagnetic system, as can
be deduced comparing Figs. 1 and 2.
In conclusion we suppose that both in nanometric grain
powders and in manganese substituted manganites (Figs.
1 and 2 respectively) the magnetic structure is
characterized by a nanometric distribution of defects that
below a definite dimension threshold gives rise to
superparamagnetic effects.
La0.63Ca0.37MnO 3 - sol gel synthesis
H ac = 2 Oe 333 Hz
0.02
0.05
χ' (emu/g Oe)
χ' (emu/g Oe)
0.06
0.015
0.04
0.03
0.01
0.02
0.005
x' 600 ºC-5h
0.01
x' 700 ºC-15h
100
150
200
0
300
0.002
250
χ''(emu/g Oe)
0.007
0.006
χ''(emu/g Oe)
0
0.0015
0.005
0.004
0.001
0.003
0.002
0.0005
0.001
0
100
150
200
T(K)
0
300
250
Figure 1 AC magnetic susceptibility of two samples
characterized by different grain size: ~10 nm (600°C5h) and ~30 nm (700°C-15h).
Zero Field Cooled
Field Cooled
m (emu / g Tesla)
9
La0.25Ca0.75Mn0.92Cr0.08O3
µ0H = 0.05 T
6
3
La0.25Ca0.75MnO3
0
0
50
100
150 200
T(K)
250
300
350
Figure 2 DC magnetic measurements of unsubstituted
and Mn-substituted samples
(1) P. Schiffer et al., Phys. Rev. Lett. 75, 3336 (1995).
(2) A. Moreo, S. Yunoki, E. Dagotto, Science 283, 2034 (1999).
(3) M. Fäth et al., Science 285, 1540 (1999).
(4) S. J. L. Billinge et al., Phys. Rev. B 62, 1203 (2000).
(5) C. Castellano et al., Solid State Commun. 136, 244 (2005).
(6) N. Mathur et al., Nature Mat. 3, 207 (2004).
(7) P. Levy et al., Phys. Rev. B 65, 140401 (2002); Hueso and
Mathur, Nature 427, 301 (2004).
(8) M. Gaudon et al., Solid State Sciences 4, 125 (2002).
(9) P. Dey et al., Phys. Rev. B 73, 214425 (2006).
P 4.18
A multi-frequency EPR study on TiO2 colloidal
nanocrystals: a closer insight on the catalytic
activity
M. Fittipaldi1, C. Sangregorio1, D. Gatteschi1, N.
Grassi2, M. L. Curri3, R. Comparelli3, M. Striccoli3, A.
Agostiano3,4
1
INSTM - Dipartimento di Chimica, Università di
Firenze, via della Lastruccia 5, 50019 Sesto Fiorentino,
Italy
107
2
Chiodellic
Dipartimento di Chimica Fisica “M.Rolla”, Università
di Pavia, Viale Taramelli 16, 27100 Pavia, Italia,
[email protected]
b
Paul Scherrer Institute, Swiss Light Source, 5232
Villigen PSI, Switzerland
c
CNR - IENI Sede di Pavia, Viale Taramelli 16, 27100
Pavia, Italia
-INFN sezione di Firenze, via B. Rossi 1, 50019 Sesto
Fiorentino (FI)
3
CNR-IPCF Sez. Bari c/o Dipartimento di Chimica,
Università di Bari, via Orabona 4, 70126 Bari, (Italy)
4Dipartimento di Chimica, Università di Bari, via
Orabona
4,
70126
Bari,
(Italy);
maria.fittipaldi.unifi.it
a
TiO2 nanocrystals (NCs) have attracted much attention
due to their remarkable photocatalytical activity [1]. It
has been widely demonstrated the dependence of the
catalytic activity of TiO2 NCs on the synthetic route
and, accordingly on the surface chemical status [2]. For
this purpose a deeper characterization has been carried
out on the TiO2 NCs by means of a multifrequency EPR
study, in order to achieve a deeper understanding of the
catalytic systems. Here, we report on EPR
measurements performed at X-band (9 GHz), Q-band
(35 GHz), and W-band (95 GHz) at various
temperatures with and without UV irradiation.
Differently shaped NCs, nanorods (NRs) or nanodots
(NDs), obtained by using two distinct synthetic routes,
namely hydrolytic and non.hydrolytic and carrying
diverse capping molecules at the surface, oleic acid (hTiO2) and TOPO (nh- TiO2), respectively, have been
investigated in order to evaluate a possible relation
between the structural properties and the specific
catalytic activity of the NCs. The EPR study presented,
carried out by using a multi frequency approach, has
demonstrated to be an extremely valuable tool for the
elucidation of the structural properties of the
investigated systems. At low temperature, UV excitation
of this semiconductor promotes electrons from the
valence band to the conduction band. The generated
electrons in the conduction band, as well as the holes in
the valence band, can be trapped either at the Ti sites or
at the surface oxygen sites, giving rise to paramagnetic
species that are detectable by EPR. The EPR spectra
enable the identification of the different sites at which
the charges are trapped.
Moreover, an extensive elemental analysis has been
performed on the NC samples by using Particle Induced
X-ray Emission (PIXE) analysis. Such measurements
have allowed to carefully characterize, either
qualitatively and quantitatively, the composition of the
amount of purity of the samples. The obtained results
well agree with the picture that comes out form the EPR
investigation, providing useful insight for the
elucidation of the (photo)catalytic behaviour of the
systems.
[1] O. Carp, Progress in Solid State Chemistry (2004) 32,
33.
[2] R. Comparelli, E. Fanizza, M. L. Curri, P. D.
Cozzoli, G. Mascolo, R. Passino, Agostiano Applied
Catalysis B: Environmental (2005) 55, 81.
Rare earth cobaltates of general formula Ln1-xAxCoO3
(Ln = rare earth, A=alkaline or alkaline earth metal) show
interesting structural, magnetic and transport properties,
which are sensitive to the average ionic radius of the Asite cations and are closely related to the availability of
different oxidation and spin states for the Co ion.
The research interest in cobalt containing oxides ranges
over a wide variety of fields, from sensor devices and
catalysts that oxidize CO and CH4 or reduce NO [1,2] to
components in solid oxide fuel cells [3], from the unusual
thermoelectric behaviour [4,5] to the peculiar magnetic
properties [6], up to the latest discovery of
superconductivity in layered systems such as
Na0.3CoO2.1.3H2O [7].
In this study we aimed at clarifying the effect of
aliovalent cation doping on the structural and transport
properties of NdCoO3 as a function of temperature by
covering a temperature range of applicative interest for
catalyst and sensor activity, i.e. the high-temperature
region.
A previous computational study on the effect of
aliovalent doping in NdCoO3 has pointed out that on the
Nd site, Ca2+ and Sr2+ are predicted to be the most
favourable dopants; for alkaline earths, the solution
energies strongly depend on the dopant size and Na is in
this case the most favourable dopant.[8] Therefore,
powder samples of composition NdCoO3, Nd0.9Na0.1CoO3
and Nd0.8Ca0.2CoO3 were prepared by conventional solid
state reaction. The amount of the two dopant ions has
been chosen in order to ensure the same oxygen
vacancies concentration for the two compositions, in
agreement with the different oxidation state of the
aliovalent dopants.
Neutron and x-ray powder diffraction data have been
combined to carefully determine lattice constants and
atomic positions while four probe direct current
conductivity and thermoelectric power measurements
allowed us to follow the thermal evolution of the
transport properties of these compounds.
The dramatic improvement of the room temperature
conductivity of Nd0.8Ca0.2CoO3 with respect to the pure
and the Na-doped compound is explained in terms of a
different spin-state for the Co ions within this structure.
The experimental data and the Co environment analysis
here discussed, in particular bond lengths distortion and
bending angles, are fully consistent with a spin state (low
to intermediate) transition in NdCoO3. The higher
conductivity and the absence of anomalies in the thermal
expansion makes the Ca-doped compound more attractive
than the pure NdCoO3 in view of possible applications.
Acknowlegment
This work was financially supported by the EC-funded
Project NOVOPOLY (Contract no. STRP 013619) and
MIUR.
1. L. Forni, I. Rossetti, Appl. Catal. B 2002, 38, 29.
2. L. Malavasi, C. Tealdi, G. Flor, G. Chiodelli, V. Cervetto, A.
Montenero, M. Borella, Sens. Actuators B 2005, 105, 407.
3. B.C.H. Steele, Solid State Ionics 1996, 86-88, 1223.
4. A. Maignan, D. Flahaut, S. Hebert, Eur. Phys. J. B 2004, 39,
145.
5. R. Robert, S. Romer, A. Reller, A. Weidenkaff, Adv. Eng.
Mater. 2005, 7, 303.
6. J. Androulakis, P. Migiakis, J. Giapintzakis, Appl. Phys. Lett.
2004, 84, 1099.
7. K. Takada, H. Sakurai, E. Takyama-Mutomachi, F. Izumi,
R.D. Dilanian, T. Sasaki, Nature, 2003, 422, 53.
P 4.19
Correlation between transport properties and
lattice effects in the NdCoO3 based catalysts and
sensor materials
G. Flora, C. Tealdia, L. Malavasi a, F. Gozzob, G.
108
8. C. Tealdi, L. Malavasi, C.A. J. Fisher, M. S. Islam, J. Phys.
Chem. B 2006, 110, 5395.
1. Farkye N. Y.; International J. Dairy Technology , 2004, 57,
(2-3), 91.
2. Hu et al., Biotechnol. J., 2006, 1, 75.
3. Hearn et al., J. Biochem. Biophys. Methods, 1996, 31, 165.
P 4.20
P 4.21
Challenges In Biocatalysis: Immobilization Of
Porcine Pepsin In Mesoporous Silicas
Luminescent nanocrystal modified epoxy
photoresist for the fabrication of 3-D high
aspect-ratio microstructures
Haresh G. Manyara*, Simonetta Tumbioloa,b, Enrica
Gianottia, Salvatore Colucciaa, Osamu Terasakib
a
Dipartimento di Chimica IFM and NIS - Centre of
Excellence, University of Torino, via P. Giuria 7, 10125
Torino, Italy . E-mail: [email protected]
b
Structural Chemistry, Arrhenius Laboratory, Stockholm
University, S-10691 Stockholm, Sweden
C. Ingrosso1, V. Fakhfouri2, M. Striccoli3,A. Voigt4, G.
Gruetzner4, M. L. Curri3, J. Brugger2
1
Dipartimento di Chimica, Università di Bari, via
Orabona 4, 70126 Bari, (Italy)
2
Microsystems
Laboratory,
Ecole
Polytechnique
Fédérale de Lausanne (EPFL), Station 17, CH-1015
Lausanne, Switzerland.
3
CNR-IPCF Sez. Bari c/o Dipartimento di Chimica,
Università di Bari, via Orabona 4, 70126 Bari, (Italy)
4
Micro resist technology GmbH, Koepenicker Str. 235,
Haus 2111, 12555 Berlin Germany
E-mail: [email protected]
Pepsin, an acidic protease has high commercial
importance in cheese manufacture from milk with global
sales value of cheese amounting to 34000 US $ per
annum [1]. There have been many attempts to immobilise
pepsin however its bulky nature hinders its diffusion
inside the porous systems, and hence its fixation is
restricted to covalent binding on synthetic and natural
polymers and inorganic oxides. In this regard large pore
mesoporous silica molecular sieves are highly favoured
materials due to their high surface area and well defined
pore geometry. We herein report a successful, simple and
convenient methodology for encapsulation of Porcine
Pepsin into the pure silica MCM-41 and SBA-15 by
physical adsorption. MCM-41 and SBA-15 were chosen
as suitable hosts because their channel-pores with
uniform diameter are arranged in the two dimensional
hexagonal p6mm symmetry. The enzyme amount that can
bind to these mesoporous supports (94 mg/g for MCM-41
and 169 mg/g for SBA-15) is much higher than for other
inorganic supports [2,3]. Pepsin adsorption followed
Langmuir adsorption isotherm. The maximum
equilibrium adsorption amount of Pepsin into SBA-15
mesopores is ≈ 179 mg/g and maximum equilibrium
adsorption amount of Pepsin into MCM-41 mesopores is
≈ 119 mg/g. The dissociation constant values for
Pepsin/SBA-15 (0.48) and Pepsin/MCM-41 (0.28)
indicate fairly strong interaction of Pepsin with the
surface. The hybrid materials were subsequently
modified by functionalisation with Aminopropyl
Triethoxy Silane (APTES) to encapsulate the Pepsin
inside the mesopores. This functionalisation has reduced
the diameter of the pore, preventing the loss of enzyme
from the surface in the reaction medium.
Recently many efforts have been directed towards the
fabrication of nanocomposite materials based on an
organic matrix combined with nanometer sized inorganic
nanoparticles, due to its high impact to transfer the
unique size dependent properties of the nanoparticles into
highly processable materials.[1] Specific electrical,
magnetic, mechanical, chemical and optical properties
can be thus added to the organic moiety, preserving at the
same time its intrinsic properties.[2] Epoxy based photoresists are excellent candidates for novel composite
materials, since they possess superior lithographic
properties. This class of materials can provide
homogeneous layers over a wide range of thicknesses and
patterns having structures with high aspect-ratio and
nearly vertical sidewalls can be obtained by using
standard near ultra violet (UV) optical lithography. In the
past, this class of photosensitive materials have
revolutionized the manufacturing of Microsystems,[3]
while later they have been used for micromechanical
applications and microsystems as microfluidic systems,[4]
packaging,[5] scanning probes,[6] and, thanks to the
convenient optical properties, for optical waveguides[7]
and near-field optical probes.[8] At present, one of the key
points in these materials comes from the lack of any
inherent complex functionality; hence the current
challenge is to add new properties to the photo-resist
matrix by means of nanocrystals (NCs) maintaining the
structurability of the photosensitive resist by UV
lithography. In this perspective, only few examples are
reported in literature on the use of nanoparticle modified
photostructurable composites.[9-16]
Several routes can be followed for the preparation of a
NC based polymer nanocomposite. For instance the
choice of a suitable ligand for NCs can ensure a proper
interaction between NCs and the host matrix and
consequently a homogeneous dispersion. Alternatively
the organic component can be properly functionalized
with suitable chemical groups, which enable an effective
interface with nanoparticles.[17]
Luminescent nanocrystals (NCs) have a great potential as
single photon sources and lasers and may be implemented
in integrated optical devices.[18] Such NCs have also
numerous advantages, such as controlled size-dependent
electronic and optical properties, large optical gain,
intense fluorescence ompared with other visible
The hybrid materials were characterised by XRD, TEM,
Volumetric (N2 sorption), FT-IR and DR-UV-Vis
techniques. The physico-chemical characterization of
these materials has confirmed the presence of the pepsin
inside the pores of the inorganic materials. The catalytic
activity of Pepsin/MCM-41 and Pepsin/SBA-15 was
evaluated by peptic hydrolysis of a dipeptide, Z-Lglutamyl-L-tyrosine. The immobilized pepsin exhibited
high catalytic activity in hydrolysis of Z-L-glutamyl-Ltyrosine.
109
fluorophores, i.e. organic dyes, and immunity from
photobleaching.
Our approach has generally intended to handle NCs and
host polymer (photoresist etc.) as separate entities, being
the nanocomposite preparation decoupled from the “ex
situ” NC synthesis very flexible and prone to be largely
customized. Such scheme allows also a wider choice of
the two components, since: i) on one side a wide range of
high quality NCs can be afforded by using the more
advanced synthetic routes to carefully control size and
size dispersion, ii) the same flexibility can be attained on
the definition of type and formulation of the host polymer
composition. This procedure appears to be very
convenient in the case of photostructurable composites,
which could be influenced by chemical modification
procedures of the photosensitive moiety, or by the
specific reactivity of the NC surface toward the host
environment both resulting detrimental for the final
structurability of the material.
We present a novel approach to further advance this field
by combining light emitting NCs with a negative tone
photosensitive epoxy based resist. Colloidal methods
have been used to synthesize luminescent cadmium
selenide NCs with tuneable size coated by a shell of zinc
sulfide
(CdSe@ZnS)
exhibiting
size-dependent
optoelectronic properties. In this work the NC
incorporation relies on the selection of a common solvent
able to safely disperse pre-synthesized organic capped
nanoparticles into the host photoresist. The media used
for dispersion have been demonstrated to play a
significant role on the photoluminescent (PL) efficiency
of emitting NCs, in addition to the synthetic
parameters.[19] A combined effort has been made both on
the resist formulation and on the NC solubility
investigation, in order to define such solvent effective for
the single resist component and to enable a homogeneous
dispersion of the NCs in the final photoresist formulation.
The original spectroscopic characteristics of the obtained
composite material have been studied as a function of the
solvent characteristics and described in terms of physical
interaction with the solvent itself. Then, films of NC
modified photoresist have been patterned and the overall
UV-structuring capability of the final material has been
demonstrated. The preservation of the NC distinctive
optical properties of the fabricated microstructured
patterns has been finally confirmed. The morphology of
the patterned structures have been also investigated and
compared with those of the unmodified photoresist.
Finally, the presented results open new perspectives
toward the micro/nano patterning of original
functionalized photosensitive materials tailored for the
fabrication
of
highly
integrated,
functional
MEMS/NEMS with inherent photonic characteristics and
activities.
525. 10. Zhang, N.; Xie, J.; Guers, M.; Varadan, V. K.; Smart
Mater. Struct. 2003, 12, 260. 11. Damean, N.; Parviz, B. A.;
Lee, J. N.; Odom, T.; Whitesides, G. M.; J. Micromech.
Microeng. 2005, 15, 29. 12. Jiguet, S.;. Bertsch, A; Hofmann,
H.; Renaud, P.; Adv. Func. Mater. 2005, 15, 1511. 13. Jiguet, S.;
Bertsch, A.; Hofmann, H.; Renaud, P.; Adv. Eng. Mater. 2004, 6,
719. 14. Xu, X.; Thwe, M.; Shearwood, C; Liao, K; Appl. Phys.
Lett. 2002, 81, 2833. 15. Cho, J. - D.; Ju, H.- T.; Park, Y. –S.;
Hong, J.-W.; Macromol. Mater. Eng. 2006, 291,1155. 15. Jiguet,
S.; Bertsch, A.; Hofmann, H.; Renaud, P.; Adv. Eng. Mater,
2004, 6, 719. 16. Liu, H.; Edel, J. B.; Bellan, L. M.; Craighead,
H. G.; Small 2006, 4, 495. 17. Thang, Z.; Kotov, N. A.; Adv.
Mater. 2005,17, 951. 18. Zhang, C. L.; Xu, T.; Butterfield, D.;
Misner, M. J.; Ryu, D. Y.; Emrick, T.; Russel, T. P.; Nano Letter
2005, 5, 357. 19. Cui, Y.; Bjork, M.; Liddle, A.; Sonnichsen, C.;
Boussert, B.; Alivisatos, P.; Nano Letter 2004, 4, 1093. 20.
Zhou, D. J.; Bruckbauer, A.; Abell, C.; Klenerman, D.; Kang,
D.; J. Adv. Mater. 2005, 17, 1243. 17. Potapova, I.; Mruk, R.;
Prehl, S.;. Zentel, R; Baschè, T.; Mews, A.; J. Am. Chem. Soc.
2003, 125, 320. 18 Eisler, H. J.; Sundar, V. C.; Bawendi, M. G.;
Walsh, M.; Smith, H. I.; Klimov, V.; Appl. Phys. Lett. 2002, 80,
4614. 19 Klimov, V. I.; McBranch, D. W.; Leatherdale, C. A.;
Bawendi, M. G.; Phys. Rev. B 1999, 60, 13740.
P 4.22
Characterization
of
nanocrystalline
semiconductor/metal phthalocyanine hybrid
junctions and applications as photoconverter
and sensor devices
C. Ingrosso1, P. Cosma1,2, P. Fini2, M. L. Curri2, G.
Giancane3, L. Valli3, A. Agostiano1,2
1
Dip. di Chimica, Univ. di Bari, via Orabona 4 I-70126
Bari, (Italy)
2
CNR IPCF - Sez Bari c/o Dip. di Chimica, Univ. di Bari,
via Orabona 4 I-70126 Bari, (Italy).
3
Dip. di Scienza dei Materiali, Univ. di Lecce, via
Arnesano
1,
73100
Lecce,
(Italy;
[email protected]
In the last decade hybrid junctions formed of thin films of
organic molecules and inorganic nanometer-sized
semiconductors have been considered appealing
frameworks due to the fruitful combination of the
peculiar intrinsic properties of both materials that can be
exploited in a wide range of applications such as light
energy conversion and sensor devices. Phathalocyanines
(Pcs) and Metal Phthalocyanines (M(II)Pcs) are
promising materials, as the suitable designing of their
aromatic macrocycle leads to numerous and different
outstanding optical, chemical, electrochemical and
semiconducting properties, which can be widely
exploited in the transduction processes for sensors[1] and
utilized in the sensitization processes of photoconversion
devices. Indeed, the incorporation and the modification of
the metal ion at the centre of the macroring and/or the
peripheral groups[2-4] can result in the modulation of the
spectroscopic properties, improving their performance as
sensitizers, and in the modification of the sensibility and
selectivity of the Pc based active layers towards several
analites. Further, these powerful peculiarities and the
high chemical and thermal stability, make Pcs appealing
materials not only for energy conversion and sensor
devices but also for a wide range of applications in which
Pcs are involved as catalyst, optical data storage
component5, photoactive material for the photodynamic
therapy, photo-sterilizing of blood6 optical limiting
substance7, non linear optical material8, active
photoreceptor in laser printing system9 as light emitting
Acknowlegment
This work was financially supported by the EC-funded
Project NOVOPOLY (Contract no. STRP 013619).
1. Balazs, A. C.; Emrick, T.; Russell, T. P.; Science 2006, 314,
1107. 2. Kickelbick, G.; Prog. Polym. Sci. 2003, 28, 83. 3.
McDonald, S. A.; Cyr, P. W; Levina, L.;. Sargent, E. H; Appl.
Phys. Lett. 2005, 85, 2089. 4. Jenke, M.G.; Schreiter, C.; Kim,
G.M.; Vogel, H.; Brugger, J.; Microfluidics and Nanofluidics
2006 published on line. 5. Krassow, H.; Campabadal, F.; LoraTamayo, E.; Sen. and Act., A: Physical 2000, 82, 229. 6.
Genolet, G.; Brugger, J.; Despont, M.; Drechsler, U.; Vettiger,
P.; de Rooij, N. F.; Anselmetti, D.; Rev. Sci. Instr. 1999, 70,
2398. 7. Kim, J.-S.; Kang, J.-W.;. Kim, J.-J; Jap. J. Appl. Phys.
2003, 42, 1277. 8. Kim, G. M.; Kim, B. J.;. Ten Have, E. S.;
Segerink, F.; Van Hulst, N. F.; Brugger, J.; J. MicroscopyOxford, 2003, 209, 267. 9. Wiche, G.; Goettert, J.;. Song, Y;
Hormes, J.; Kumar, C. S. S. R.; Int. J. Comput. Eng Sci. 2003, 4,
110
material10 and CD-R dye11. Conversely, inorganic
colloidal oxide nanocrystalline (NC) semiconductors are
good candidates for energy conversion and sensing
applications due to the peculiar properties which exhibit
in nanoscopic regime size as the large surface-to-volume
ratio that results in a wide superficial area which improve
the interactions between the surface atoms and the
environment and in very efficient charge transfer
processes. Further, colloidal chemistry routes offer the
possibility to synthesized on large scale NC materials
tuning effectively their morphology, size and size
distribution affecting as well the porosity, the structural
stability and the topography of the related NC- based
films, being the latter fundamental for the charge transfer
efficiency, sensitivity and reproducibility of the manifold
interaction-based processes. Finally, colloidal methods
allow to obtain organic NC solutions easily processable
as thin films with handy solution-based deposition
techniques. NC materials can thus be relevant for wide
areas of applications, ranging from energy conversion to
photocatalysis [12,13], and as active layer for sensor
devices, as functional materials in electro- and
photocromic devices, light emitting diodes and
intercalation batteries [14].
Single component-based devices, typically present
limited performances and the conjunction of both
materials in hybrid junctions will offer the possibility to
overcome these drawbacks due to the efficient charge
transfer processes occurring at the organic/inorganic
interfaces. Thus, the NC peculiar properties such as the
size tuneable band gap when properly synthesized in
quantum confinement regime15,16, and the convenient
engineering of Pc counterpart, provide the opportunity to
optimize the energy level mismatch17,18, thus improving
the efficiencies of the charge exchange processes which
can occur in photoconverter and sensor devices.
In this work an extensive chemical physical
characterization of the D4h MPcs, zinc phthalocyanine
(Zn(II)Pc), magnesium phthalocyanine (Mg(II)Pc) and
tetrakis-(isopropoxy-carbonyl)-copper-phthalocyanine
(TIPCu(II)Pc) and of the related hybrid junctions formed
of ZnO and TiO2 NCs is presented. UV-vis spectroscopic
techniques have been used to widely characterize MPcs
in organic solvents as CHCl3, Py, DMSO and DMF. The
study reveals as the different chemical structure affects
the MPc solubility as well as their aggregation tendency
and shows as the different centre metal atom strongly
effects the MPc spectroscopic response. Advanced
deposition technique as Langmuir-Blodgett has been used
to deposit highly ordered films of the CHCl3 soluble
TIPCu(II)Pc and its behaviour at the air/water interface
has been analyzed on the basis of the Langmuir theory
and monitored by Brewsted Angle Microscopy (BAM).
A wide spectroscopic and topographic characterization
has been conducted also on thin films of both the bare
MPcs and of the related hybrid junctions by means ATR
and AFM investigations. The morphologies of the bare
phthalocyanine films has been found to be strongly
affected by the solvent, temperature and concentration,
while that of the corresponding hybrid films is only
defined by the topography of the oxide NC
semiconductor film. Finally, the efficiency of the hybrid
systems has been studied both when they integrated in
photoelectrochemical cells and in sensor devices. The
study shows that the performances are strongly affected
by the temperature treatment of the films, by the solvent,
by the shape and nature of the NC oxide and by the
concentration of both the NC oxide and MPc.
Struct. 1998, 450, 239. 4. Wróbel, D.; Boguta, A.; Ion, R. M.; J.
Mol. Struct. 2001, 595, 127. 5. Ferraudi, G.; In Phthalocyanines,
Properties and Applications; Leznoff C.C.; Lever A.B.P., Eds.;
VCH: New York, 1989, 1, p.291. 6. Sharman, W. H.; Allen, S.
M.; van Lier, J. E; In Methods in Enzymology; Packer L., Sies. 7.
Qu, S.; Gao, Y.; Zhao, C.; Wang, Y.; Fu, S.; Song, Y.; Wang,
D.; Qiu, J.; Zhu, C.; Chem. Phys. Lett. 2003, 367, 767. 8.
Nordwood, R. A.; Sounik, J. R.; Appl. Phys. Letter 1992, 60,
295. 9. Mizuguchi, J.; Rihs, G.; Karfunkel, H. R.; J. Phys. Chem.
1995, 99, 16217. 10. Fujii, A.; Yoshida, M.; Ohmori, Y.;
Yoshino, K.; Jpn. J. Appl. Phys. 1996, 35, L37. 11. Namba, N;
In Phthalocyanine-Chemistry and Functions; Shirai Y.,
Kobayashi N., Eds.; IPC: Tokyo, 1997, p.247. 12. Cozzoli P.D.;
Comparelli R.; Fanizza E.; Curri M.L.; Agostiano A.; Laub D.;
J. Am. Chem. Soc. 2004, 126, 3868. 13. Wrobel D.; Goc J.; Ion
R.M.; J. Mol. Struct. 1998, 450, 239. 14. Grätzel M., in: Kamat
P.V., Meisel D. (Eds.), Semiconductor Nanoclusters—Physical,
Chemical, and Catalytic Aspects, Elsevier Science B.V.,
Amsterdam, 1997, p. 353. 15 Alivisatos, A.P.; J. Phys. Chem.
1996, 100, 13226. 16. Alivisatos, A.P.; Science 1996, 271, 933.
17 Grem, G.; Leitzky, G.; Ullrich, B.; Leising, G.; Adv. Mater.
1992, 4, 36. 18. Greenham, N. C.; Moratti, S. C.; Bradley, D. D.;
Friend, R.; Holmes, A. B.; Nature 1993, 365, 628
P 4.23
Modification of UHMWPE processed by laser
ion implantation
A. Lorusso1, F. Paladini2, L. Velardi1, D. Margarone3, N.
Campo4, L. Torrisi3, V. Nassisi1
1
Laboratorio di Elettronica Applicata e Strumentazione,
LEAS, Department of Physics, University of Salento
& INFN - Lecce, Via Provinciale Lecce-Monteroni,
73100 Lecce – Italy Tel. +39 0832 297495, Fax. +39
0832 297482, E-Mail: [email protected]
2
Laboratorio di Dinamica Nonlineare, NDL, Department
of Physics, University of Salento, Via Provinciale LecceMonteroni, 73100, Lecce-Italy
3
Department of Physics, University of Messina; Ctr.
Papardo 31, 98166 S. Agata, Messina-Italy
4
Dip.to Di Chimica Ind. E Ing. Dei Materiali, Università
di Messina, Ctr. Di Dio, 98166 S. Agata-Messina-Italy
ABSTRACT
Ultra-high-molecular-weight-polyethylene (UHMWPE)
is nowadays utilized in many fields, such as biomedicine, engineering and microelectronics due its
excellent chemical and physical properties.
In medicine, for instance, UHMWPE is employed in
many prosthesis devices for its high degree of
homogeneity, high mechanical stability and good elastic
properties similar to the hard tissue and the bone1.
Nevertheless, UHMWPE suffers serious alterations
especially when it is submitted to high mechanical
dynamical stresses, to high temperature and to high
corrosive environment. Special attention is voted to the
UHMWPE wear as a result of friction against hard
surfaces at body temperature typically for polyethylene
employed in many mobile prosthesis.
Ion implantation is a good tool to modify the surface
characteristics of the polymer in order to reduce the
friction wear increasing the whole device lifetime.
In this work, an improvement of the wear resistance of
UHMWPE is attempted by using a new ion implantation
technique induced by laser-generated plasma at high ion
dose.
The “implantation machine” consists of a KrF excimer
laser operating at 248 nm wavelength (5 eV photon
1. Valli, L.; Advance in Colloid and Interface Science, 2005,
116, 13. 2. Wróbel, D.; Boguta, A.; J. Photochem. Photob. A:
Chem. 2002,150, 67. 3. Wróbel, D.; Goc, J.; Ion, R. M.; J. Mol.
111
energy) and a vacuum chamber made of stainless steel.
The laser power density was of 3.5·108 W/cm2 which was
able to produced a very high density plasma characterized
by ions, electrons and neutral particles. Applying an
accelerating voltage, ions with a current density of the
order of 10 mA/cm2 were extracted and accelerated up to
40 kV and implanted onto UHMWPE substrates2,3.
Polyethylene modifications were obtained in the first
superficial layers (up to few hundreds nanometres) by
implanting ions of carbon or titanium at a particle fluence
of the order of 1011 ions/cm2 per pulse. The implantation
was carried out applying some thousands of laser shots at
a low repetition rate, ranging from 0.1 to 1 Hz. This low
rate value was indispensable to avoid arcs in the plasma.
Our preliminary results showed the surface property
modifications of UHMWPE after ion implantation. The
surface micro-hardness analysis was performed by
applying the “scratch test” method. The SEM photos of
Fig. 1 show a typical example of the test performed on
the implanted and no-implanted UHMWPE. The
resulting scratch width is about 50 µm for the implanted
sample (red area of Fig 1a), i.e. 80% lower than that one
obtained for no-implanted sample as shown the red area
reported in Fig. 1b. Therefore, the smaller scratch
indicates a lower tip deep in the sample surface, i.e. that a
little increment of the surface hardness occurred in the
implanted samples.
a)
P 4.24
Structure, orientational order and dynamics of
HAB by 2H and 13C NMR spectroscopy and
DFT calculations
Alberto Marini1,2, Lucia Calucci3, Marco Geppi1, Carlo
Alberto Veracini1
1
Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via Risorgimento 35, 56126 Pisa,
Italy
2
Scuola Normale Superiore di Pisa, Piazza dei Cavalieri
12, 56126 Pisa, Italy
3
Istituto per i Processi Chimico-Fisici del CNR, via G.
Moruzzi 1, 56124, Pisa, Italy
Structural, orientational order properties and dynamics of
4,4’-heptylazoxybenzene (HAB) were critically reinvestigated in its nematic and smectic A phases
combining 2H and 13C NMR techniques, as well as
theoretical DFT calculations. To this aim, two
isotopomers, HAB-D4 and HAB-D8, partially and fully
deuterated on the phenyl rings, respectively, were also
studied.
b)
Figure 1: SEM photos for scratch test. a)UHMWPE
implanted by C ions; b) no-implanted UHMWPE.
Furthermore, preliminary results have been obtained
about the wettability modifications of the polymer after
ion implantation. The wettability test was performed by
the contact angle measurement. The Fig. 2 shows two
examples of contact angle measurements. The Fig 2a)
shows the wettability test performed on the surface of the
no-implanted UHMWPE, while the Fig. 2b) shows the
wettability test made on the surface of UHMWPE sample
implanted by Ti ions. The ion implantation modified the
contact angle value reporting the values of 96° and of
88.5° for no-implanted sample and for the implanted one,
respectively. This result induces to conclude that the
processed samples were characterized by an improvement
of hydrophilicity respect to no-processed ones.
a)
13
C-{1H} NMR static spectra were recorded on HAB by
means of the Linear-Ramped Cross-Polarization
technique, under SPINAL-64 decoupling1 in the whole
mesomorphic range. 13C resonances were assigned with
the help of solution state spectra and DFT calculations
performed using Gaussian’032. Chemical shift anisotropy
(CSA) trends with temperature were obtained for all of
the chemically distinguishable carbons. Moreover,
deuterium quadrupolar and dipolar (deuterium-proton)
splittings were determined from 2H NMR quadrupolar
echo spectra, recorded on HAB-D4 at different
temperatures within the mesophases. 13C and 2H data
were used to determine the complete order matrix and the
angle between the para axes of the HAB phenyl rings
through a non-linear least-squares global-fitting
procedure, in which geometrical parameters and 13C
shielding tensors calculated at the DFT level of theory
(B3LYP/6-31G(d)
and
MPW1PW91/6-311+G(d,p)
combination of hybrid functional and basis set; GaugeIncluding Atomic Orbitals, GIAO
method3) were
employed. The results were discussed in comparison with
those previously obtained from deuterium data only4.
13
C spin-lattice relaxation times (T1) were determined for
all three compounds throughout the liquid-crystalline
phases. The combined analysis of these data with the
already available deuterium relaxation times5 allowed
detailed information to be obtained on HAB
reorientational dynamics in the mesophases.
b)
Figure 2: wettability test a) no-implanted UHMWPE; b)
UHMWPE sample implanted by Ti ions with 6000 laser
shots.
1. L. Torrisi, A. Visco and N. Campo, Bio-Medical Mater. and
Engeneering, 2004 , 14, 251.
2. F. Belloni, D. Doria, A. Lorusso, V. Nassisi, L. Torrisi, L.
Calcagnile, G. Quarta, D. Bleiner and D. Manno, Nucl. Instrum.
Meth. B 2005, 240, 36.
3. A. Lorusso, J. Krasa, K. Rohlena, V. Nassisi, F. Belloni and
D. Doria, Appl. Phys. Lett. 2005, 86, 081501.
112
crystalline, while surface terminations did not exhibit any
flat and sharp profile, suggesting a highly disordered,
amorphous-like surface structure (more evident in the
case of HA-A). The same features were observed for HAB/0.1 and HA-B/0.5.
As for the state of adsorbed water, MIR (νOH and δH2O
regions) and NIR [(νout+δ)H2O region] spectra indicated
that the hydration layer in direct contact with the HA-A
and HA-B surfaces was mainly constituted by water
molecules involved in both coordination to surface Ca2+
through their oxygen atom, and a strong H-bonding with
neighbour phosphates. Moreover, H-bonding states of
H2O molecules different from those in bulk water were
found to be extended up to three molecular layers
adsorbed on the first one. Outgassing at 300 °C of HAA resulted in an inward relaxation of ca. 60% of surface
cations, not longer accessible to water. Interestingly, the
IR spectra of adsorbed CO, used as a highly sensitive
vibrational molecular probe, monitored the increase
Lewis acidity of a relevant part of Ca2+ sites left exposed
on the surface.
The presence of Mg2+ in HA-B/0.1 and HA-B/0.5
resulted in a progressively higher ability of the materials
to bind water at the surface. Because of the absence of
modification of the surface texture (by UHR-TEM) this
feature should be a consequence of the higher Lewis
acidity of such surface cations monitored by IR spectra of
adsorbed CO.
HA-A material was used for the investigation of the
interaction with BSA, also. The adsorption isotherms
appeared to follow the Hill model of cooperative
adsorption [4]. A maximum amount of adsorbed protein
corresponding only to ca. 30% or 40% of the theoretical
full monolayer, considering the side-on or end-on
adsorption mode, respectively, was obtained. Such a
finding indicated that only a fraction of surface sites
exhibit structural and energetic features resulting on the
ability to absorb the protein. Many studies pointed out
that the interaction between protein and surfaces should
involve the dehydration of both moieties. We obtained a
direct evidence of this process by recording the NIR
spectra of HA-A (Fig. 1) in the bare form (solid line)
and after BSA absorption (dash-dot line), both outgassed
at room temperature. It can be observed that the
(νout+δ)H2O appeared significantly decreased in intensity
after BSA adsorption, indicating that protein displaced
H2O molecules originally adsorbed on Ca2+ cations.
1. Fung, B. M.; J. Magn. Reson. 86, 160, 2005.
2. Gaussian 03, Revision B.05. Frisch, M.J.; et al., Gaussian,
Inc., Pittsburgh PA, 2003.
3. Ditchfield, R.; Mol. Phys. 27, 789, 1974.
4. Catalano, D.; Forte, C.; Veracini, C.A.; Emsley, J. W.;
Shilstone, G. N.; Liq. Cryst. 2, 345, 1987.
5. Domenici, V. Czub, J.; Geppi, M.; Gestblom, B.; Urban, S.;
Veracini,C. A.; Liq. Cryst. 31, 91, 2004.
P 4.25
Surface structure of nanohydroxyapatite: effects
on water and protein adsorption
Luca Bertinetti, Raffaella Ceschino, Gabriele Alberto,
Daniele Bollati, Gianmario Martra
Department of Chemistry IFM, NIS Center of Excellence
, Università di Torino, via P.Giuria 7, 10125 Torino,
Italy, [email protected]
Introduction. The key role of the surface features of
biomaterials has been recognized, leading to the
definition, at the beginning of 2000’s of the concept of
“biological/biomedical” surface science [1,2] The
unravelling of the ensemble of surface processes and
phenomena actually occurring in vivo is still a challenge,
but there is a general consensus in setting the causal
sequence: i) biomaterial surface structure, ii) states of
adsorbed water molecules and iii) states of adsorbed
proteins, that then rule the fate of the interaction of the
implant with cells.
On such a basis, we investigated the effect of the
modification of the surface features of nanosized,
biomimetic hydroxyapatite (HA) materials by i) partial
exchange of Ca2+ with Mg2+, ii) outgassing at 300 °C,
that produces significant changes in the HA surface
structure [3] on the interaction with water and a model
protein, namely BSA.
Experimental. HA nanoparticles were obtained as the
precipitate produced by: i) dropping a H3PO4 solution in
a Ca(OH)2 aqueous dispersion (material hereafter
indicated as HA-A), and ii) by mixing solutions of
Ca(NO3)2 and (NH4)2HPO4 (material hereafter indicated
as HA-B). Mg2+ ions were introduced in aliquots of HAB by ion-exchange, performed by soaking them in 0.1M
and 0.5M MgCl2 solutions (samples HA-B/0.1 and HAB/0.5, respectively). BSA absorption was carried out by
suspending HA-A at 37 °C in protein solutions of due
concentration, obtained by dissolving BSA in a phosphate
buffer (pH= 7.4).
A multi-technique approached was used. Investigation
down to a subnanometric level of the surface structure
and morphology of the materials was carried out by
UHR-TEM (Jeol EX4000 and 3010). Insights on states of
adsorbed water were obtained by Mid- (transmission) and
Near IR (diffuse reflectance, DR) spectra of samples kept
in atmosphere with controlled levels of water vapour
pressure. Quantitative aspects of protein adsorption on
HA-A were evaluated by measuring (via UV
spectroscopy) the decrease of the BSA concentration in
solutions where the samples were suspended. NIR (DR
mode) and MIR (ATR mode) spectroscopy were also
used for the study of surface water-protein interactions
and structural features of adsorbed BSA, respectively.
Results and discussion. HRTEM data indicated that both
HA-A and HA-B materials were made of nanoparticles
elongated in the direction of the crystallographic c-axis,
with length in the 50-150 and 30-60 nm range,
respectively. For both materials the particle core appeared
0.03
protein
(ν + δ) NH
Kubelka-Munk
0.02
0.01
protein
2νin CH2
(νout + δ) H2O
0.00
6000
5500
5000
-1
Wavenumber (cm )
Figure 1: NIR spectra (DR mode) of HA-A before (solid
line) and after (dash-dot line) the absorption of BSA.
Both spectra were recorded after recovery of the HA
powder from the buffered aqueous suspension, washing,
drying at r.t. and outgassing at r.t. for 1 h.
MIR spectra (ATR, after exchange with D2O) indicated
that adsorbed BSA retained the native secondary
113
structure almost unchanged.
BSA adsorption was carried out on HA-A preoutgassed at 300 °C also. Interestingly, the amount of
adsorbed protein appeared slightly increased for all the
points of the adsorption isotherm. Such a finding strongly
suggests that for hydroxyapatite the amount of adsorbed
protein (or, at least, of albumin) is not strictly related to
the hydrophilicity of the material (amount of adsorbed
water), but to the presence of surface sites with a proper
local structure, resulting in cationic centres with a higher
polarizing power.
carried out by SEM and XRD techniques, spectroscopic
characterisation by FT-IR, diffuse reflectance UV-VisNIR and EPR spectroscopies. FT-IR and DR UV-VisNIR spectra were recorded at room temperature (RT)
after a pre-treatment in O2 at 723 K, treatments in
vacuum at increasing temperature up to 673 K and
subsequent treatments in dry oxygen at the same
temperatures. After the same treatments, EPR spectra
were recorded in X-band at 77 K.
XRD analysis shows that the Mo-W samples are not
single phases, but they are constituted mainly by two
crystalline structures. Only MoW4 shows a predominant
mixed phase (98.3±0.4 wt.%) with the structure of βMoO3 (#89-1554 JCPDS) and W occupancy of 0.22. A
second phase (pure monoclinic WO3 (#83-0950 JCPDS))
is present in very low amount (1.7±0.4 wt.%).
Preliminary XRD results for MoW1 and MoW0.25
indicate high percentages of two mixed phases:
Mo0.6W0.4O3 (#76-1280 JCPDS) and β-MoO3 for MoW1
sample; Mo0.29W0.71O3 (#76-1279 JCPDS) and
Mo0.14W0.86O3 with the structure of monoclinic WO3 for
MoW0.25 sample. XRD pattern of MoW4 recorded after
reducing treatment in vacuum at 723 K shows the
appearance of peaks due to a crystalline phase different
from those of the completely oxidised sample and related
to the presence of Mo0.85W0.15O2.91 sub-stoichiometric
phase (37.8±1.0 wt.%). This effect is completely
reversible for treatment in oxygen at 723 K. Preliminary
results for MoW1 and MoW0.25 indicate that the
treatment in vacuum at 723 K causes changes in the
relative amounts of the phases previously found for the
oxidised samples and not the formation of substoichiometric phases. These results enlighten only for
MoW4 mixed oxide the capability of losing oxygen not
only from the surface but also from the bulk up to a
reversible structural rearrangement. On the other hand,
pure MoO3 and WO3 do not change their XRD patterns
after reducing treatments in the same conditions.
FT-IR spectra recorded after reducing treatments in
vacuum at increasing temperature show the increase of
broad absorptions in the MIR region for pure MoO3, WO3
and for MoW4 sample. Absorptions in the MIR region
can be related to the presence of electrons trapped at
oxygen vacancies. Otherwise, MoW1 and MoW0.25
show only the increase of the tail related to absorptions
present at higher energies. As a matter of fact, in the VisNIR region all the pure and mixed samples show, beside
the absorption edge related to the valence band–
conduction band transition, the increase of broad
absorptions on increasing the outgassing temperature (see
Fig. 1 as an example). These absorptions are related to
the presence of polarons. Therefore, the absorptions in
the Vis-NIR region can be interpreted as: (i) intervalence
charge transfers of the type [M5+-O-M6+]−[M6+-O-M5+]
also called polaronic transitions; (ii) M5+ d-d transitions;
(iii) M5+-O2- ligand to metal charge transfers.
Acknowledgments. Dr. A. Tampieri and Dr. E Landi at
CNR-ISTEC (Italy), and Prof. C. Rey and Dr. C. Drouet
at INPT-ENSIACET (France), are acknowledged for
having kindly provided HA-A and HA-B related
materials, respectively.
References
1.. Kasemo, B; Surf. Sci., 2002, 500, 656-677.
2. Wilson C. J.; Clegg, R. E.; Leavesley, D. I.; Pearcy M. J.;
Tissue Eng, 2005, 11,1-18.
3. Bertinetti L.; Tampieri A.; Landi E.; Ducati C.; Midgley, P.A.;
Coluccia S.; Martra G.; J.Phys Chem. C, 2007, 111, 4027-4035.
4. Luo Q.; Andrade J.D.; J. Colloid Interf. Sci., 1998, 200, 104113
P 4.26
Structural and spectroscopic characterisation of
Mo1-xWxO3-δ oxides.
S. Morandia, G. Ghiottia, M. C. Paganinia, E. Giamelloa,
M. Binib, D. Capsonib, V. Massarottib.
a
Dip. di Chimica I.F.M. and NIS Centre of Excellence,
Via
Giuria
7,
10125
Torino.
e-mail:
[email protected]
b
Dip. di Chimica Fisica “M. Rolla” e IENI-CNR, Viale
Taramelli 16, 27100 Pavia.
MoO3 and WO3 are well known metal oxides
extensively studied for their application in gas sensing
devices [1,2]. The interesting optical and electronic
properties also make them attractive as electrochromic
devices [3]. Moreover, molybdenum and tungsten oxide
based materials are highly important compounds in
selective oxidation catalysis [4]. They show the capability
to lose oxygen in reducing conditions and to restore the
lost oxygen in oxidising ones. The introduction of oxygen
vacancies in MoO3 and WO3 gives rise to electrical
conductivity. Thus, sub-stoichiometric molybdenum and
tungsten oxides are semiconductors. Upon reduction M6+
cations are reduced to M5+ or M4+. The additional charge
carriers are coupled to the lattice distortion generated in
their surroundings, called polaron. Frequently, metal
oxide combinations were tailored to achieve desired
properties and to modify their electrical behaviour. As an
example, recent studies focused on MoO3-WO3 mixed
oxides report on their promising gas sensing potential [5].
In this work we reported about the preparation and
characterisation of Mo-W mixed oxides with different
Mo/W molar ratios (4, 1 and 0.25, named MoW4, MoW1
and MoW0.25, respectively) and for comparison
purposes also pure MoO3 and WO3. All the samples were
prepared by precipitation of the hydrated oxides from
aqueous solutions of ammonium heptamolybdate and
ammonium paratungstate in the right ratio.
Morphological and structural characterisations were
0.8
Kubelka-Munk
0.6
e
0.4
d
0.2
0.0
25000
114
f
c
ba
20000 15000 10000
-1
Wavenumbers (cm )
5000
CoAPO-5 samples, prepared by direct hydrothermal
synthetic methods, were characterized by XRD, TEM,
Surface area measurements, DR-UV-Vis and FTIR
techniques. DR-UV-Vis spectra were used to identify the
local geometry and redox behaviour of cobalt centres. In
the calcined samples tetracoordinated Co2+ ions sites
were observed. Upon oxidation at 673 K, the conversion
of a small fraction of Co2+ ions into Co3+, which are
reversibly transformed into Co2+ ions by hydrogen
treatment at 573K was observed [1]. FTIR spectra were
utilized to study the surface binding nature and reactivity
of NO and CO molecular probes with cobalt ions. FTIR
spectra of NO adsorbed on both oxidized and reduced
CoAPO-5 showed the presence of two distinct Co2+(NO)2
complexes (1893 and 1812 cm-1, 1921 and 1844 cm-1)
with different stability, confirming the presence of two
different kinds of coordination environment for Co2+ in
the matrix [2]. No evidence for the formation of NO2δ+
species on the surface of the catalyst on both oxidized
and reduced samples could be found. Adsorption of CO
resulted in the formation of two different bands at 2184
cm-1 and 2047 cm-1. While the former is typical of CO
linearly adsorbed on framework tetrahedral or tetragonal
Co2+ ions, the latter, which appears only on reduced
samples, can be explained with the formation of Co0 or
Co+ carbonyls. This indicates the presence of small
extraframework clusters with reversible redox behaviour
that could not be detected by XRD or DR-UV-Vis
techniques.
Figure 1. Vis-NIR spectra recorded at RT for MoW1 sample
after pre-treatment in oxygen at 723 K (a) and subsequent
outgassing at RT (b), 373 K (c), 473 K (d), 573 K (e) and 673 K
(f).
EPR spectra confirm the presence of electrons
trapped at oxygen vacancies for pure MoO3, WO3 and
MoW4 with the presence of isotropic signal at g-value
characteristic of electron that does not interact with a
neighbouring nucleus (g = 2.00). This is the only one
signal for WO3 and for this reason it is possible to
postulate that the absorption observable in the Vis-NIR
region is related to EPR-silent bipolarons. For MoO3,
MoW4, beside the isotropic signal, and for MoW1 and
MoW0.25 several EPR signals related to Mo5+ and W5+
in different states of coordination and symmetry are
observable (see Fig. 2 as an example).
All the electronic absorptions in the MIR and VisNIR region and EPR signals are gradually eroded for
treatments in oxygen at increasing temperature. This
confirms that they are related to defect originated from
oxygen loss.
f
e
1. Barrett, P.A.; Sankar, G.; Catlow, C.R.A; Thomas, J. M.;
Journal of Physical Chemistry, 1996, 100, 8977-8985. 2.
Gianotti, E.; Marchese, L.; Martra, G.; Coluccia, S.; Catalysis
Today, 1999, 54, 547-552.
d
c
a=b
3000
3200
3400 3600
B (Gauss)
3800
4000
Figure 2. EPR spectra recorded at 77 K for MoW0.25
sample after pre-treatment in oxygen at 723 K (a) and
subsequent outgassing at RT (b), 373 K (c), 473 K (d), 573 K (e)
and 673 K (f).
P 4.28
Effect of the substrate type/composition and
deposition techniques on the photocatalytic
activity of semiconducting nanocrystalline films
for environmental applications
1. Prasad, A. K.; Gouma, P. I., Kubinski, D. J.; Visser, J. H.;
Soltis, R. E.; Schmitz, P. J.; Thin Solid Films, 2003, 436, 46-51.
2. Choi, Y. G.; Sakai, G.; Shimanoe, K.; Yamazoe, N.; Sens and
Act. B, Chem., 2004, 101, 107-111. 3. Djaoued, Y.; Ashrit, P. V.;
Badilescu, S.; Brüning, R.; J. Sol-Gel Sci. Tec., 2003, 28, 235244. 4. Dieterle, M.; Mestl, G.; Jäger, J.; Uchida, Y.; Hibst, H.;
Schlögl, R.; J. Mol. Catal, 2001, 174, 169. 5. Galatsis, K.; Li,
Y.; Wlodarski, W.; Cantalini, C.; Passacantando, M.; Santucci,
S.; J. Sol-Gel Sci. Tec., 2003, 26, 1097-1101.
A. Pannielloa, R. Comparellib, D. Disoc, A. Licciullic, G.
Mascolod, A. S. Franzae, M. Striccolib, A. Agostianoa,b,
M.L. Currib
a
Università di Bari – Dip. Chimica, Via Orabona 4,
Bari, I-70126, Italy
b
CNR-IPCF Sede Bari, c/o Dip. Chimica – Via Orabona
4, Bari, I-70126, Italy; [email protected]
c
Dipartimento Ing. Dell’Innovazione, Universita` di
Lecce, via per Arnesano, Lecce, I-73100, Italy
d
CNR-IRSA – Sez. Bari, Viale De Blasi, Bari, I-70100,
Italy
e
Salentec SRL, via dell’esercito 8, 73020 Cavallino Le,
Italy
P 4.27
Redox behaviour of Co species in microporous
CoAPO-5: a spectroscopic study
M. Vishnuvarthan a,b*, G. Berlier b, E. Gianotti b, D. Davit
b
, V. Murugesan a, S. Coluccia b
a
Department of Chemistry, Anna University, Chennai600025, India. e-mail: [email protected]
b
Dipartimento di chimica IFM, Università di Torin, V.P.
Giuria 7, I-10125 Torino, Italy.
Nanostructured semiconductors immobilized onto
appropriate substrates are very promising in catalysis
applications thanks to the matched effects of their very
high surface area, ascribed to the improved surface to
volume ratio of the nanoparticles, and the facile recovery
of the catalyst, due to the effects of the deposition.[1]
Therefore considerable efforts are devoted to identify the
more suitable substrates and the deposition techniques to
set up the optimal conditions in order to develop efficient
photocatalysts that could be easily recovered from the
Transition metal ions incorporated aluminophosphate
molecular sieves such as CoAPOs, show attractive
catalytic properties due to the variable and reversible
oxidation state of cobalt (Co2+/Co3+) in addition to the
BrØnsted Co2+(OH)Al functionality. Among these,
115
reaction system and likely recycled in following
experiments.[2-4]
The present work is devoted to the optimization of
deposition conditions of nanostructured titania thin films
for environmental photocatalysis. For this purpose
anatase TiO2 nanorods and nanodot were prepared both
by synthesis in hot coordinating solvent and sol-gel
process. The as-prepared materials were characterized by
XRD and TEM measurements. The films roughness and
catalyst adhesion was investigated by AFM and SEM
measurements
either
before
and
after
the
photodegradation experiment.
The films were prepared by exploiting two different
deposition techniques (casting and dip-coating) and
different supports (glass slides, glass fibers, alumina
fibers), in order to get the optimal deposition conditions.
The photocatalytic activity of the obtained films was
evaluated in the oxidative photodegradation of an organic
dye (Methyl Red) in aqueous matrix under UV
irradiation.
Photocatalysis experiments were monitored by UV-Vis,
HPLC-MS and TOC analysis. Finally, the experimental
condition which showed the higher photoactivity and
better catalyst adhesion were replicated in a scaled up
reactor in order to test the catalyst activity in large scale
processes.
Acknowledgment. This work was partially supported by
Progetto MIUR D.M. no. 1105 (9 October 2002) funding
programme and by Explorative Project “Photocatalytic
degradation of organic pollutants in aqueous solutions by
nanostructured semiconductors” funded by “Apulia”
Region within the Scientific Research Framework
Program 2006
for optical, electronic, catalytic, and biomedical
applications1 Current research has been focused on onedimensional nanoparticles such as nanorods (NRs) since
the morphological anisotropy results in very complex
physical properties.2 In fact, the plasmon absorption of
gold NRs splits into two bands corresponding to the
oscillation of the free electrons along and perpendicular
to the long axis of the rods. In particular, the resonance of
the longitudinal mode is red shifted and strongly depends
on the nanorod aspect ratio.3 Water soluble gold
nanospheres and nanorods have been synthesized by
using various methods such as templating,4
photochemistry,5 seeding6 and electrochemistry7.
In this work, we propose a silver ion mediated
photochemical synthesis of gold nanoparticles (NPs) in
micellar template under UV irradiation. We performed a
systematic study on the role of Ag+ ions in directing the
growth of gold NRs, in order to elucidate the mechanism
that produces anisotropic particles rather than spheres.
The effect of reaction time and silver ion concentration
has been deeply investigated. The samples have been
characterized by UV-Vis-NIR absorption spectroscopy,
High Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive Spectrometry (EDS),
Inductively Coupled Plasma (ICP), and Extended X-ray
Absorption Fine Structure Spectroscopy (EXAFS)
measurements. Moreover the size and shape distribution
has also been investigated by statistical analysis of the
experimental data. The overall obtained results allowed
us to finely tune the size and the shape distribution of
gold NPs and to propose a reasonable mechanism
describing the role played by silver ions in directing the
growth of gold NRs.
Acknowledgment. This work was financially supported
by the EC-funded Project NOVOPOLY (Contract no.
STRP 013619).
1. Comparelli, R.; Fanizza E.; Curri M. L.; Cozzoli P. D.;
Mascolo G.; Passino R.; Agostiano A.; Applied Catalysis B:
Environmental, 2005, 55, 81-91.2. Pozzo R. L.; Giambi J. L.;
Baltanas M. A.; Cassano A. E.; Catalysis Today 2000, 62, 175187. 3. Horikoshi S.;Watanabe N.; OnishiH.; Hidaka H.;
Sermone N.; Applied Catalysis B: Environmental, 2002, 37,
117–129. 4. Yu H.; Lee S.C.; Yu J.; Ao C.H.; Journal of
Molecular Catalysis A: Chemical, 2006, 246, 206–211
1. Daniel, M.C.; Astruc, D.; Chem. Rev. 2004,104, 293. 2. Kim,
F.; Kwan, S.; Akana, J.; Yang, P. J. Am. Soc. 2001, 123, 4360. 3.
Link, S.; El-Sayed, M.A.; J. Phys. Chem. B 1999, 103 ,84108426. 4. Bohmer, M. R.; Fokkink, L. G. J.; Scho¨nenberger, C.;
van der Zande, B. M. I. J. Phys. Chem. B 1997, 101, 852. 5.
Esumi, K.; Matsuhisa, K.; Torigoe, K. Langmuir 1995, 11, 3285.
6. Murphy C. J.; Jana N. R. Adv. Mater. 2002, 14, 80. 7. Yu, Y.
Y.; Chang, S. S.; Lee, C. L.; Wang, C. R. C. J. Phys. Chem. B
1997, 101, 6661-6664.
P 4.29
Silver ions mediated photochemical synthesis of
water soluble gold nanoparticles with control
over size and morphology
P 4.30
Protein Adsorption on Chemically and
Topographically
Nanopatterned
Polymer
Surfaces
T. Placidoa, R. Comparellia, P.D. Cozzolib M. Striccolia,
G. Capitanic, F. Giannicid M.L. Curria,
a
CNR-IPCF Sez. Bari, c/o Dip. Chimica – Via Orabona
4, Bari, I-70126, Italy – [email protected]
b
National Nanotechnlogy Laboratory of CNR-INFM,
Distretto Tecnologico ISUFI, via per Arnesano Km 5, I73100 Lecce, Italy
c
Università di Bari – Dip. Geomineralogico, Via
Orabona 4, Bari, I-70126, Italy
d
Università di Palermo – Dip. di Chimica Inorganica e
Analitica - Parco d'Orleans II, I-90128 Palermo, Italy
C. Satriano, G.M.L. Messina, and G. Marletta
Laboratory
for
Molecular
Surfaces
and
Nanotechnologies (LAMSUN), Department of Chemical
Sciences, University of Catania and CSGI, Viale Andrea
Doria, 6, 95125 Catania, Italy. [email protected]
The preferential adsorption of two model globular
proteins, lactoferrin (Lf) and albumin (HSA) was
investigated onto chemically nanostructured polysiloxane
surfaces, as function of the pattern geometry and
chemical contrast.
The nanopatterned surfaces consisted of 2D nanopore
arrays, having hydrophilic internal area (O2-plasma
treated polysiloxane) surrounded by hydrophobic
polysiloxane or the reverse.
Gold nanoparticles with nanometer-scale dimensions are
of great interest due to their unusual physical and
chemical properties with respect to their bulk counterpart.
The optical properties of metal nanoparticles are tunable
throughout the visible and near-infrared region of the
spectrum as a function of size, shape, aggregation state
and local environment, thus making them very promising
116
The pattern geometry was modulated by using two
different methods. The first one was based on colloidal
self-assembly driven by dewetting, followed by polymer
infiltration due to capillarity. The second method, based
on spin coating of suitable colloidal and polymer
solutions, to vary experimental parameters as ionic
strength, pH, solution concentrations.
The nanometric features of adsorbed proteins were
investigated by AFM, while the corresponding
homogeneous surfaces were studied by QCM-D, for the
adsorption kinetics, and XPS, for chemical structure and
coverage of the protein adlayers.
A good spatial separation of HSA and Lf was obtained,
prompted by opposite preferential adsorption behaviours,
involving increased adsorption of Lf and HSA into the
hydrophilic or hydrophobic areas of the nanopores,
respectively.
The driving chemical factors were identified in terms of
surface free energy and chemical termination of the
different surfaces.
anatase (101).
1. Saunders, V.R.; Dovesi, R.; Roetti C., Orlando, R.; ZicovichWilson, C.M.; Harrison, N.M.; Doll, K.; Civalleri, B.; Bush, I.J.;
D’Arco, P.; Llunell, M.; CRYSTAL03 User’s Manual, Università
di Torino, Torino (2003). 2. Dovesi, R.; Saunders, V.R.; Roetti
C., Orlando, R.; Zicovich-Wilson, C.M.; Pascale, F.; Civalleri,
B.; Doll, K.; Harrison, N.M.; Bush, I.J.; D’Arco, P.; Llunell, M.;
CRYSTAL06 User’s Manual, Università di Torino, Torino
(2006). 3. Scaranto, J.; Ph. D. thesis, University of Venezia,
2006: (see web site
http://venus.unive.it/molspectragroup/LowResolutionTiO2/TiO.
htm.)
P 4.32
Photocatalytic H2 production from water
splitting on one step flame synthesised TiO2 and
Au/TiO2
Elena Selli, Gian Luca Chiarello, Ilenia Rossetti, Lucio
Forni
Dipartimento di Chimica Fisica ed Elettrochimica,
Università degli Studi di Milano, Via Golgi 19, 20133
Milano, [email protected]
P 4.31
A quantum-mechanical study on the adsorption
of CO on TiO2: comparison between the Lewis
acidity of the rutile (110) and the anatase (101)
surfaces.
TiO2 and 1 wt% Au/TiO2 were synthesised by a
continuous, single-step flame spray pyrolysis method
(FP) [1,2] and characterized by BET, XRD, HRTEM and
UV-vis reflectance analyses. Both materials consisted of
crystalline well dispersed 5-10 nm nanospheres, with
high surface area (106 m2 g-1). XRD analysis showed the
presence of ca. 75% anatase and 25% rutile, whereas no
peaks ascribable to metal gold could be recognized,
because of the low noble metal loading. Both materials
exhibited a UV-vis adsorption threshold at ca. 400 nm;
the gold containing oxide also displayed the typical
plasmonic band of gold nanoparticles (< 20 nm), centred
at 550 nm, i.e. red shifted compared to the pure gold
plasmon peak (520 nm), indicating interaction between
gold and the titania support.
The photocatalytic activity of the materials was tested in
a appositely set up, closed recirculation laboratory scale
photoreactor (Fig. 1), designed to investigate the activity
of suspended particles in water photosplitting, to produce
H2 and O2. The reactor consisted of a 45 mL,
magnetically stirred quartz vessel (A) containing the
photoactive suspension, connected to a closed stainless
steel circulation system, in which an inert gas (nitrogen)
was continuously flowed by means of a bellow pump (C).
The analysis of the species evolved from the aqueous
suspension under irradiation was performed by gas
chromatography with TC detector (D), after calibration
by injections of known volumes of H2 (or O2) through a
six ways valve (E).
Jessica Scarantoa, Santi Giorgiannia
a
Università Ca’ Foscari di Venezia, Dorsoduro 2137,
30123, Venezia, [email protected]
Titanium dioxide represents one of the most interesting
metal oxides as it is widely employed in the field of
heterogeneous catalysis. The two natural allotropic forms
mainly used are the rutile and anatase ones, whose the
most stable surfaces are represented by the (110) and the
(101), respectively.
Here, we present the main results obtained from a
periodic quantum-mechanical study on the adsorption of
carbon monoxide on the two surfaces. This study has
been done to compare the electrophilicity of the two
different surface Lewis acid sites (Ti4+). In fact, as it is
well-known, the CO molecule binds to the cation of the
metal oxide and the magnitude of the shift of the
vibrational frequency of the CO stretching gives
information on the strength of the adsorbate-substrate
interaction. All the calculations have been performed at
DFT/B3LYP level using the CRYSTAL program1,2. The
two surfaces have been simulated by two slabs whose
thickness converges with respect both the structural
relaxation and the surface formation energy3. The
adsorption has been investigated by considering different
surface coverages and periodicities; the obtained
adsorbate-substrate system has been characterised by
means of not only the binding energy but also the
interaction and distortion ones. The lateral effects
between the CO molecules, consisting in a direct and a
surface-mediated repulsion, have been analysed by using
a simple model of nearest and next-nearest neighbours;
this model allows also the determination of the energies
in the limit of an isolated adsorbed molecule.
Furthermore, the vibrational frequency of the adsorbed
CO molecule has been computed. The study reveals that
the adsorbate-substrate interaction is slightly stronger in
the case of the CO-rutile system and then, it is possible to
conclude that the surface Lewis acid site of the rutile
(110) is slightly more electrophilic than that of the
Fig. 1: sketch of the experimental set up
117
The light source was an iron halogenide mercury arc
lamp, emitting in the 315-400 nm wavelength range with
an irradiation intensity of 3 x 10-7 Einstein s-1 cm-2 on the
reactor. All photocatalysts (14 mg) were suspended in
water, in the absence or in the presence of 6 vol.%
methanol as sacrificial agent, sonicated for 20 min and
thoroughly flushed with inert gas in the photoreactor,
before starting irradiation.
H2 production occurred at constant rate, apart from a sort
of initial induction time, possibly dependent on the
residual oxygen content of the suspension and on
temperature (usually 35°C under irradiation).
The FP-prepared TiO2 photocatalyst displayed a higher
activity with respect to the commercial Degussa P25,
usually employed as benchmark of photocatalytic activity
(0.27 vs 0.17 mmol H2 h-1). H2 production on the FPsynthesised Au/TiO2 photocatalyst was so high (6 NmL
produced in 2 h), that outgassing was required every 2 h,
to prevent H2 overpressure. Successive irradiation cycles
were thus performed, with an outgassing in the dark in
between (Fig. 2). No induction period in hydrogen
evolution on Au/TiO2 was ever observed, with only a
slight decrease in the H2 production rate in successive
cycles (7.89, 7.53 and 7.18 mmol H2 h-1, hence ca. 25
times higher with respect to the Au free FPphotocatalyst).
20
dark and
outgassing
Monteroni, 7310 Lecce-Italy
3
Institute for Microelectronics and Microsystems (IMM)
of CNR, Unità di Lecce, Via Provinciale LecceMonteroni, 73100 Lecce – Italy
We present a new “implantation machine” utilized to
process SiO2 samples by Si ions. The practical
consequence consists to obtain composite materials
containing silicon nanocrystals (NCs) in SiO2 matrix
obtained by ion implantation and annealing. These NCs
have the potentiality to emit photons in the visible light
region which is very useful in integrated photonic and
optoelectronic devices. The production Si NCs by ion
implantation offers an advantage respect to other
techniques, i.e a controllable dose of ions at a given
depth.
The ion source was developed by laser ablation of Si
target. The employed laser is an excimer laser operating
at 248 nm wavelength, 23 ns pulse time duration
providing a power density of 3.5x108 W/cm2. The laser
beam strikes the target producing a very high density
plasma which expands adiabatically into the vacuum. The
success of the present device was reached inserting a
removable expansion chamber (EC) which allowed an
initial free expansion of the plasma before the ion
extraction reducing, in this way, the probability of arcs
during the acceleration which could decrease the
implanting ion dose. Figure 1 shows the experimental
apparatus developed at LEAS laboratory where it is
possible to see the EC equipped by a quartz window (W)
in order to close the plasma in the proximity of the target.
The EC works as anode, while a ground electrode (GE)
as cathode. On GE, we put the sample to be implanted.
For metallic samples we utilized a GE having a central
hole behind which the samples were placed. The
extracted ion dose, utilizing 40 keV accelerating voltage,
was estimated by using a fast Faraday cup (FC) in front
the ion beam. It was negatively polarized (500 V) in
order to collect only plasma positive particles. By our
experimental conditions, the applied ion dose was of the
order of 1012 ions/cm2 per laser pulse.
1wt% Au/TiO2
mmol H2 / g catalyst
16
12
8
4
0
0
1
2
3
4
5
6
7
8
irradiation time [h]
Fig. 2: Hydrogen production from photocatalytic water splitting
on FP-synthesised 1% Au/TiO2.
Thus, FP appears to be a very promising preparation
method for the direct synthesis of TiO2–based
photocatalysts active in water splitting.
1. Chiarello, G.L.; Rossetti, I.; Forni, L.; Journal of Catalysis,
2005, 236, 251-261. 2. Mädler, L.; Stark, W.J.; Pratsinis, S.E.;
Journal of Materials Research, 2003, 18, 115-120.
Si nanocrystals obtained in SiO2 matrix by low
energy ion implantation
Figure 1. Schematic drawing of the experimental
apparatus. GC: Generation Chamber; EC: Expansion
Chamber; W: quartz window IF: Insulating Flange; T:
Target; GE: Grounded Electrode; FC: Faraday Cup. The
accelerating gap is established between the EC, biased at
high voltage, and the GE.
L. Velardi1, A. Lorusso1, M. Traversa2, P. Prete3, V.
Nassisi1, N. Lovergine2
1
Laboratorio di Elettronica Applicata e Strumentazione,
LEAS, Department of Physics, University of Salento &
INFN - Lecce, Via Provinciale Lecce-Monteroni, 73100
Lecce – Italy Tel. +39 0832 297495, Fax. +39 0832
297482, E-Mail: [email protected]
2
Laboratorio di Fisica e Tecnologia dei Semiconduttori,
Department of Innovation Engineering, University of
Salento, CNISM, Unità di Lecce, Via Provinciale Lecce-
Considering the whole charge due to practically to the
ions with +1 charge state 1,2 and applying one thousand
laser shots, we obtained a total implanted dose of 1015
ions/cm2.
The experiment was performed with a p-type (B doped)
Si(100) wafer of 225 µm thickness, target. The wafer was
suitably rotated during the implantation process in order
to avoid the formation of a unique crater, which may
decrease the ion emission yield. Samples consisted of 300
P 4.33
118
concentrate on H-SAPO-34 material, where the presence
of three distinct Brønsted sites (one of them showing an
acid strength comparable to zeolite homologues) was
recently proved by a careful spectroscopic analysis. In
this work, a quantitative method for the determination of
total Brønsted content is proposed. This method is based
on the combination of FTIR data (spectra of CO and
NH3) and gravimetric analysis of ammonium
decomposition. The measured value is combined with the
relative fraction of the three Brønsted sites estimated
before, in order to calculate the extinction coefficients of
distinct sites with different acidity. The calculated values
are of general validity for chabasite-like SAPO materials
and are of great importance for catalysts optimization.
nm thick thermal SiO2 films on Si(100) and were
implanted with some thousand shots at a maximum
accelerating voltage of 40 kV. The laser was operated at
0.5 Hz repetition rate. The vacuum chamber was
evacuated by two turbo-molecular pumps down to 10-6
mbar.
Implanted samples were subsequently annealed at 1000
°C in a tubular resistance furnace flowed with 6.0N pure
N2 gas for a few hours to induce Si precipitation and the
formation of Si NCs. In order to evidence changes in the
material crystallinity degree upon annealing, asimplanted ad annealed samples were then studied by Xray diffraction (XRD) in both Bragg and glancing
incidence geometry. An example of XRD pattern
performed on no-implanted and implanted and annealed
samples is reported in Fig. 2. The dimension of the
generated nanocrystals was estimated of about 36 nm by
using Debye-Scherrer equation.
b)
a)
Figure 2. X-ray diffraction is used to value the
effectiveness of the implantation. a) no-implanted
sample; b) implanted and annealed at 1000°C sample
obtained at an incident angle.
1) V. Nassisi and A. Pedone, Rev. Sci. Instrum. 2003, 74, 68.
2) D. Doria, A. Lorusso, F. Belloni, V. Nassisi, L. Torrisi and S.
Gammino, Laser Part. Beams 2004, 22, 461.
P 4.34
New methodology for Brønsted quantification in
microporous
materials:
FTIR
and
themogravimetry
G. A. V. Martins a, G. Berlier a, G. Gatti b, S. Coluccia a,
and L. Marcheseb
a
Dipartimento di Chimica IFM, Università di Torino,
Turin I-10125 Italy, [email protected],
b
Dipartimento di Scienze e Tecnologie Avanzate,
Università del Piemonte Orientale, Alessandria I-15100,
Italy
H-SAPO-34, a silico-aluminophosphate (SAPO) with
chabazite structure and Brønsted functionality, has shown
peculiar activity and selectivity in MTO processes, and is
now central to the UOP/Norsk Hydro MTO technology.
The ability of tuning concentration and strength of
Brønsted acid sites in solid catalysts could improve the
process performances and catalysts lifetime. As a
consequence, a careful characterization of Brønsted sites
in terms of acid strength and number represents a
fundamental advance in catalysis. In this work we
119
SEZIONE
CHIMICA TEORICA E COMPUTAZIONALE
120
particles of different shapes and sizes and the calculation
of the interaction parameters for the different type of
beads in order to correctly simulate the dynamic
behaviour .
of the studied system.
Some preliminary results will be presented and discussed.
In particular, the formation of continuous surfactant
domains in PMMA has been investigated as a function of
the mixture composition. Finally a comparison of the
obtained theoretical results with the experimental data
will be shown.
P 5.1
DPD Simulations to investigate
nanocomposites morphology
polymer
E.Bianchinoa,b, S.Piottob, C. Sciancaleporea, M. L. Curric,
A. Agostianoa,c, M. Striccolic, F.Ciriacoa, F.Mavellia
a
Chemistry Department, University of Bari, Via
Orabona 4 – 70125 Bari
b
Pharmaceutical Science Department, University of
Salerno via Ponte don Melillo 84084 Fisciano (Salerno)
c
CNR-IPCF Sez. Bari c/o Chemistry Department,
University of Bari, Via Orabona 4 – 70125 Bari
DPD Simulations
Dense
polymer-particle
mixtures,
or
polymer
nanocomposites, are of major scientific and technological
interest1. Fundamental issues include equilibrium
miscibility, dispersion and spatial organization of
particles, particle-induced modification of polymer
conformation and packing, structure of the polymerparticle interface, and the calculation of new thermomechanical emerging properties. Diverse theoretical and
simulation approaches have begun to be employed to
study fundamental aspects of model polymer-particle
mixtures: Monte Carlo and Molecular Dynamics
methods, both at atomistic and coarse grain levels, and
mesoscopic methods such as like Dissipative Particle
Dynamics2 and Mean-Field Dynamics3.
In this contribution, TiO2 nanocrystals (NCs) synthesised
in surfactant solutions (hot injection method) have been
investigated4. As a consequence of the preparation
method, NCs are coated by amphiphilic molecules, i.e.
oleic acid and trioctilphosphin oxide –TOPO-, that, once
NCS are embedded in a polymer host matrix, can also
play a role in defining the morphology of the blend. This
work aims to evaluate the possibility to describe and
foresee the characteristic features of the investigated
polymer nonocomposites by using both a commercially
available software (Materials Studio® by Accelerys Inc.)
and a simulation package issued free under licence to
academic institutions (DL_MESO developed at
Daresburry Laboratory). In particular, Dissipative
Particle Dynamics has been used to simulate the
morphological features of PMMA/Oleic Acid/Colloidal
oxide NCs and PMMA/TOPO/Colloidal oxide NCs
mixtures, respectively. Indeed, this mesoscale method
applies classical simulation techniques to coarse-grained
systems. In this perspective polymer and surfactant
molecules can be thought as decomposed in a collection
of linked beads, representing homogeneous domains with
approximately the same volume. Critical points in this
approach stand on the description of NCs as rigid
Surfactant Composition
Different morphologies observed in DPD simulations of
PMMA/Oleic Acid mixtures with different compositions:
surfactant molecules are represented by blue (hydrophilic
head) and green (hydrophobic tail) spheres, while polymers
are not explicitly reported. The gray surface is the interface
between the two domains
Acknowlegment
This work was financially supported by the EC-funded
Project NOVOPOLY (Contract no. STRP 013619).
P 5.2
Polarizzabilità ed iperpolarizzabilità statiche di
semplici
molecole:
studio
degli
effetti
vibrazionali.
S. Bruzzonea, U.T. Lamannab, C. Guidottia, G.P.
Arrighinia
a
Dipartimento
di
Chimica
e
Chimica
Industriale,Università di Pisa, Via Risorgimento 35,
56100 Pisa; [email protected]
b
Dipartimento di Chimica, Università di Bari, Campus
Via Orabona 4, 70125 Bari.
In questo lavoro è presentata una valutazione delle
performance di set di base di orbitali atomici di Slater
(STO) nel calcolo di contributi vibrazionali a proprietà di
risposta elettromagnetica statica, lineare e non lineare, a
livello TDHF (Time Dependent Hartree Fock). In
particolare, i contributi vibrazionali alla polarizzabilità ed
alla prima e seconda iperpolarizzabilità statiche sono stati
valutati impiegando le formule perturbative derivate da
Bishop e Kirtman1. Queste formule, basate su una iniziale
approssimazione di tipo armonico, includono correzioni
che tengono conto dell’anarmonicità meccanica del
potenziale vibrazionale e dell’anarmonicità elettrica
dipendente dal potenziale di polarizzazione del campo
elettrico sulle coordinate vibrazionali. Il metodo richiede
preliminarmente la conoscenza della superficie di energia
potenziale in funzione delle coordinate normali della
molecola, accompagnata dal contemporaneo calcolo del
momento di dipolo elettrico totale, della polarizzabilità e
della prima iperpolarizzabilità per ogni geometria
molecolare esaminata, alla frequenza studiata. Elementi
fondamentali della procedura sono le derivate prime,
1
Wang, M.-J. Rubber Chem. Technol. 1998, 71, 520; 1999, 72,
430; Huber, G.; Vilgis, T. A. Macromolecules 2002, 35, 9204;
Vieweg, S.; Unger, R.; Heinrick, G.; Donth, E. J. Appl. Polym.
Sci. 1999, 73, 495;
Ajayan, P. M.; Schadler, L. S.; Braun, P. V. In Nanocomposite
Science and Technology; Wiley-VCH: Weinheim, 2003, p 77;
Ash, J.; Schadler, L. S.; Siegel, R. W. Mater. Lett. 2002, 55, 83;
Mackay, M. E.; Dao, T. T.; Tuteja, A.; Ho, D. L.; van Horn, B.;
Kim, H.-C.; Hawker, C. J. Nat. Mater. 2003, 2, 762.
2
Español, P., Warren, Europhys. Lett., 1995, 30, 191; P. Groot
R.D., Warren P.B. J. Chem. Phys., 1997, 107, 4423.
3
Fraaije, J.G.E.M., van Vlimmeren, B.A.C., Maurits, N.M.,
Postma, M., Evers, O.A., Hoffman, C., Altevogt, P., GoldbeckWood, G., J. Chem. Phys., 1997, 106, 4260; Altevogt, P., Evers,
O.A., Fraaije, J.G.E.M., Maurits, N.M., van Vlimmeren, B.A.C.,
J. Mol. Struct. (THEOCHEM) 1999, 463, 139.
4
Manera, M.G.; Leo, G.; Curri, M.L.; Comparelli, R.; Rella, R.;
Agostiano, A.; Vasanelli, L., Sensors and Actuators B:
Chemical, 2006, 115, 365.
121
seconde e terze di tutte queste grandezze rispetto alle
coordinate normali.
I risultati, accompagnati da dati di confronto tratti dalla
letteratura, sono presentati per piccole molecole isolate:
HF, LiH, H2O, D2O.
Levels of several types of glycosidases, such as
sialidases, have been shown to be elevated in the
interstitial fluid of tumors. In particular, over-expression
of Neu3 sialidase inhibits apoptosis and promotes cellular
proliferation. Thus, this enzyme could be a useful target
for diagnostic and therapeutic agents.1
With this aim, we propose a new gadolinium complex (2)
as molecular imaging contrast agent candidate. It consists
of a DOTA-like ligand covalently linked to the sialic acid
moiety. Based on similar examples reported in literature,2
design of this structure relies on the following hypothesis:
the sialic moiety prevents the contrast agent activity,
hindering coordination of a water molecule to the ninth
coordination site of the gadolinium ion; in presence of
sialidases, the sialic acid is cleaved from the chelate
allowing coordination of a water molecule and restoring
the contrast agent activity.
Here we present preliminary results concerning
characterization of the conformational behaviour in
aqueous solution of complex (2) performed by means of
MD simulations based on a previously developed force
fields.3 The chemical synthesis of complex (2) is
underway.
1. a) Kirtman, B.; Bishop, D.M.; Chem. Phys. Lett.,1990, 175,
601-607. b) Bishop, D.M.; Kirtman, B.; J. Chem. Phys., 1991,
95, 2646-2658.
P 5.3
Characterization of a New Candidate as
Contrast Agent for Magentic Resonance
Molecular Imaging
U. Cosentinoa, D. Piteaa, G. Morob, G.A.A Saracinob , L.
Cipollab, M. Gregorib, F. Nicotrab, A. Villac
a
Università di Milano-Bicocca, Dipartimento di Scienze
dell’Ambiente e del Territorio, Piazza della Scienza 1,
20126 Milano, Italy, [email protected]
b
Università di Milano-Bicocca, Dipartimento di
Biotecnologie e Bioscienze, Piazza della Scienza 3,
20126, Milano, Italy
c
J.W. Goethe University, Institute for Physical and
Theoretical Chemistry, Max-von-Laue-Strasse 7, D60439 Frankfurt am Main, Germany
OH
CH3CONH
O
O
N
O
N
O
O
O
O
OH
N
N
Gd
O
3+
N
N
O
O
O
(2)
1. Kakugawa, Y.; Wada, T.; Yamaguchi, K.; Yamanami, H.;
Ouchi, K.; Sato, I.; Miyagi, T.; Proc. Natl. Acad. Sci. USA,
2002, 99, 10718–10723.
2. Louie, A.Y.; Huber, M.M.; Ahrens, E.T.; Rothbacher, U.;
Moats, R.; Jacobs, R.E.; Fraser, S.E.; Meade, T.J.; Nature
Biotechnology, 2000, 18, 321-325.
3. Cosentino, U.; Moro, G.; Pitea, D.; Villa, A.; Fantucci, P.C.;
Maiocchi, A.; Uggeri, F.; J. Phys. Chem. A, 1998, 102, 46064614. (b) Villa, A.; Cosentino, U.; Pitea, D.; Moro, G.;
Maiocchi, A.; J. Phy. Chem A, 2000, 104, 3421-3429.
O
3+
N
O
O
N
Gd
O
HO
Contrast agents based on paramagnetic metals such as
gadolinium ion are routinely used in magnetic resonance
imaging (MRI) diagnostic technique to shorten relaxation
times of water protons and enhance image contrast.
Chelating
moieties
are
typically
octadentate
PolyAminoCarboxylate (PAC) ligands that form
kinetically and thermodynamically stable complexes with
gadolinium. The ninth coordination site of the ion, not
saturated by the ligand, allows fast exchanging water
molecules to transmit the paramagnetic relaxation effect
to bulk solvent.
Contrast agents for clinical use, such as the Gd-DOTA
complex (1), are confined to extracellular spaces and
distribute nonspecifically throughout vascular and
interstitial tissues.
O
O
OH
O
P 5.4
(1)
Theoretical and experimental studies of layered
alkylamine-aluminophosphates.
Development of new MRI contrast agents concerns
systems presenting increased sensitivity and specificity
toward biological targets: this defines a new class of
contrast agents suited for the so called molecular
imaging. In general, the design of these new contrast
agents involves the linkage of the gadolinium complex
with moieties able to bind to specific receptors, cell
surface antigens, proteins, or sensible to enzymatic
activity.
M. D’Amorea, C.Bisioa, G. Talaricob, M. Cossia, L.
Marchesea.
a
Dipartimento di Scienze e Tecnologie Avanzate,
Università del Piemonte Orientale “A. Avogadro”, Via
Bellini
25/G,
15100
Alessandria,
[email protected]
b
Dipartimento di Chimica, Università di Napoli
“Federico II”, Complesso di Monte S. Angelo, Via
Cintia, 80126 Napoli
122
Lamellar aluminophosphates modified by intercalation of
alkylamines are key intermediates in the synthesis of
aluminophosphates
(ALPOs)
and
silicoaluminophosphates (SAPOs) molecular sieves and
can be also used as host framework in the fields of
nanocomposites. However, until the CAL-n family of
microporous silicoaluminophosphate molecular sieves
was presented1, there were no good candidates as layered
reactants, that is lamellar aluminophosphates and
silicoaluminophosphates with structures similar to the
hydrated layered silicates. It is from the work of Cheng et
al.2, who reported the synthesis of the layered
aluminophosphate ALPO-ntu (whose empirical formula
is AlPO2(OH)2[NH2(CH2)xCH3], x=3, 5, 7), employing
amines as structure directing agents, that the perspective
to obtain ALPOs and SAPOs molecular sieves using
layered materials as precursors became possible1. In
addition, layered aluminophosphates, especially those
organically modified by intercalation of different nalkylamines, have the assets of a larger interlayer
distance and organophilic galleries between the sheets to
host either organic molecules or polymer chains.
Moreover, the interaction between organic molecules and
inorganic aluminophosphate may influence the acidity of
sites present on the surfaces and drive the interfacial
phenomena in polymer composites.
The experimental data available on this class of layered
aluminophosphates were not sufficient to fully resolve
both their local and long range structural features. For
this reason computational approaches are proposed to
model structure and surface properties of these materials
thus obtaining useful insights on their chemical
behaviour. Reliable models may also help a better
understanding of experimental data. The acidity of sites
on ALPO layers and the interactions between organic
molecule and the inorganic substrate have been
specifically addressed.
Since all experimental (X-ray powder diffraction
patterns, IR, 27Al and 31P MAS NMR) data relative to the
alkylamine-aluminophosphates are in agreement with a
kanemite-like structure, ab-initio computational models
of butylamine-ALPO-kanemite were built starting from a
reasonable structure of silica kanemite3.
The computational tools to simulate these solids were
based on density functional theory (DFT) employing
localized basis sets: both cluster and periodic models
were taken into account, and IR spectra were simulated
for optimised structures. Results were compared with the
IR experimental spectrum of butylamine-ALPOkanemite. The harmonic vibrational spectra were
computed (PBE0/6-31 G(d), LANL2DZ level) for all the
cluster minima, to identify the chemical species present
in the material and support the interpretation of the
experimental data.
Computations on cluster of ALPO surface show that the
P-OH moiety is markedly more acidic than Al-OH and
the structure of relative anion is stabilized by PO-···H-OAl hydrogen bond. The results are interpreted in terms of
an acid-base reaction between protons P-OH groups in
the inorganic layer and the butylamine molecules.
The actual position of the positive butylamonium heads
was determined by a bidimensional PBC calculation on
the ALPO layer in presence of an equivalent layer of NH3
molecules close to the surface. During the optimisation
all the surface P-OH groups reacted with NH3 molecules
and were quickly deprotonated forming NH4+ ions: as a
consequence, the Al-OH groups rotated and the
intramolecular H-bond observed in the isolated anion
were lost in favour of the stronger interaction with NH4+.
In the AlPO-NH4+ periodic layer the ammonium ion was
substituted by CH3(CH2)3NH3+ ion: the optimised
structure shows tridentate butylammonium ions i.e. the
ion interacting via three hydrogen bonds, one with
oxygen atom on Al and the other two with oxygen atoms
on phosphorous in the layer, these H bonds are not
equivalent (Fig. 1).
Fig. 1. Detail of optimized structure (PBC/PBE/6-21G level) of
a layer of butyl-ALPO-kan
This position of butylamonium ion on surface leads to a
downward shift of the -NH3+ stretching frequencies,
which were found in the region 3200-3000 cm-1 (Fig. 2),
significantly lower than the isolated NH vibration. Al-OH
groups in Butyl-ALPO-Kan point on lattice oxygens in a
well ordered network of H-bonds, and give a sharp peak
at 3584 cm-1 in the IR spectrum.
The IR spectrum presents also bands around 2550 cm-1
and 2090 cm-1, which derive from both strong H-bonds in
R-NH3+···-OP complexes and combination of rotations of
RNH3+ with the bendings at 1635 cm-1 and 1555 cm-1.
The positions of the bands strongly depends upon the
strength of hydrogen bonds between protons in R-NH3+
groups and both PO- and basic surface oxygens. The
shape of the combination bands derives from the
interactions with vibrational states of the ν (NH) band of
hydrogen bonded groups. A Fermi resonance between
fundamental stretching modes and the overtones and/or
combinations, which pronounce an Evans window around
2180 cm-1, is in fact clearly observable.
0,9
n-Butyl AlPO Kanemite
3584
0,8
Absorbance
0,7
3075
0,6
1635
0,5
1555
0,4
0,3
3500
3000
2500
2000
1500
-1
Wavenumber [cm ]
Fig.3: IR spectrum of butylammonium intercalated in ALPOkan.
1. (a): Pastore, H.O.; Coluccia, S. and Marchese, L.; Annu. Rev.
Mater. Res.,2005, 35, 351; (b): Pastore, H.O.; Martins, G.A.V.;
Strauss,M.; Pedroni, L.G.; Superti, G.B.; de Oliveira, E.C.;
Gatti , G. and Marchese, L.; Micropor. Mesopor. Mater., (in
press).
123
importante stimare quantitativamente la solubilità di
molecole organiche ed inorganiche in questi composti. La
grandezza termodinamica rilevante per stabilire
l’eventuale solubilità di un possibile soluto in un dato
solvente è il potenziale chimico in eccesso. Il potenziale
chimico in eccesso per numerosi soluti in liquidi ionici
recentemente è stato stimato teoricamente attraverso
simulazioni molecolari [1, 2] e in alcuni casi comparato a
risultati sperimentali [2]. Nel presente lavoro gli effetti
della solvatazione, tra cui appunto il potenziale chimico
in eccesso, per molecole organiche ed inorganiche (H2O,
Acetone, Metanolo e CO2) sono stati valutati seguendo
un trattamento alternativo alle simulazioni e non ancora
applicato nel campo dei liquidi ionici, basato sulla teoria
Reference Interaction Site Model monodmensionale (1DRISM)[3]. Questo metodo, che fornisce le funzioni di
distribuzione radiale atomo-atomo (g(r)) risolvendo le
equazioni integrali RISM, presenta due vantaggi: richiede
uno sforzo computazionale estremamente contenuto e le
soluzioni ottenute sono libere dal rumore statistico e dagli
artefatti numerici, tipici delle simulazioni. Inoltre, il
potenziale chimico può essere espresso analiticamente a
partire dalle funzioni di distribuzione, evitando le
difficoltà insite nelle tecniche di simulazione molecolare
sviluppate per stimare grandezze termodinamiche in
eccesso. I risultati ottenuti per una serie di liquidi ionici
modello ([mmim][Cl],[mmim][BF4 ] e [mmim][PF6])
sono in accordo qualitativo con precedenti dati ottenuti da
simulazioni MD e MC; la deviazione è data dalla
differenza tra le g(r) simulate e quelle ottenute per via
RISM. Un accordo quantitativamente più soddisfacente è
possibile tramite vari approcci [4]. Un primo
miglioramento è ottenibile introducendo delle correzioni
in grado di migliorare l’accordo delle g(r) calcolate con
quelle simulate, tramite procedure già applicate in
letteratura appositamente per il calcolo di potenziali
chimici in eccesso tramite 1D-RISM.
2.Cheng, S.; Tzeng, J.; HSU,B.; Chem. Mater. 1997, 9, 17881796.
3.Garvie, L.A.J. ; Devouard, B.; Groy, T.L.; Camara, F. ;
Buseck; P.R.; American Mineralogist, 1999, 84, 1170-1175.
P 5.5
Sviluppo e applicazione di metodi basati su
Orbitali Molecolari Estremamente Localizzati
Michela Ghittia, Alessandro Genonia,b, Stefano
Pieraccinia, Maurizio Sironia
a
Dipartimento
di
Chimica
Fisica
ed
Elettrochimica,Università degli Studi di Milano, via
Golgi 19, 20133 Milano, [email protected]
b
Quantum Theory Project, University of Florida, P.O.
Box 118435, 32611 Gainsville, Florida, U.S.A.
Gli Orbitali Molecolari Estremamente Localizzati
(ELMOs), ovvero orbitali strettamente localizzati su
frammenti molecolari, risultano essere un efficace
strumento per la costruzione della distribuzione
elettronica di sistemi di grandi dimensioni.
L’affidabile trasferibilità degli ELMOs, già ampiamente
dimostrata, è stata sfruttata nel nostro laboratorio, per
sviluppare un programma per la determinazione della
densità elettronica ab-initio di polipeptidi, attraverso
l’utilizzo di un database di ELMOs1 determinati su
molecole modello opportunamente costruite.
Poiché gli ELMOs risultano essere orbitali non
ortogonali, il calcolo della corrispondente matrice densità
risulta essere dispendioso. Per realizzare un algoritmo di
calcolo efficiente si è quindi impiegato un approccio
“Divide and Conquer”, particolarmente adatto a sfruttare
la natura localizzata degli ELMOs.
Al fine di migliorare l’accuratezza nella descrizione di
proprietà molecolari “locali”, quali ad esempio le barriere
rotazionali, è stata messa a punto una nuova strategia che
permette di rilassare selettivamente solo gli ELMOs che
rivestono un ruolo cruciale nella determinazione delle
proprietà in esame.
1. Lynden-Bell, R. M.; Atams, N. A.; Vasilyuk, A.; Hanke, C.
G.; Mol. Phys., 2002, 100, 3225 – 3229. 2. Shah, J. K.; Maginn,
E. J.; J. Phys. Chem. B, 2005, 109, 10395 – 10405. 3. Chandler,
D.; Andersen, H. C.; J. Chem. Phys., 1972, 57, 1930. 4. Kast, S.
M.; ChemPhysChem, 2004, 5, 449 – 455.
1. Genoni, A.; Ghitti, M.; Pieraccini, S.; Sironi, M.; Chem. Phys.
Lett., 2005, 415, 256 – 260. 2. Genoni, A.; Sironi, M.; Theor.
Chem. Acc., 2004, 112, 254 – 262. 3. Sironi, M., Genoni, A.;
Civera, M.; Pieraccini, S.; Ghitti, M.; Theor. Chem. Acc., in
press.
P 5.7
Synthetic, electrochemical and theoretical
investigation of encumbered triangular cluster
units
P 5.6
Potenziali chimici in eccesso in liquidi ionici
tramite 1D-RISM
Gabriele Mancaa, Alberto Albinatib, Samantha Bruzzonea,
Fabrizia Fabrizi de Bianic, Carla Guidottia, Piero Leonia,
Lorella Marchettia, Swagat K.Mohapatraa, Eliseo Ruizd,
Piero Zanelloc
M. Malvaldia, S.Bruzzoneb, C. Chiappea.
a
Dipartimento di Chimica Bioorganica e Biofarmacia,
Università di Pisa, Via Bonanno 33, 56126 Pisa.
e-mail corresponding author: [email protected]
b
Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via Risorgimento 35, 56126 Pisa.
.
a
Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, via Risorgimento 35, Pisa.56126
Email:[email protected], [email protected]
b
Dipartimento di Chimica Strutturale e Stereochimica
Inorganica, via Venezian 21, Milano
c
Dipartimento di Chimica,Università di Siena, via A.
Moro, Siena.
d
Department de Quimica Inorganica,Universidad de
Barcelona (Spain)
I liquidi ionici sono una nuova classe di sistemi organici
sempre più frequentemente studiata e utilizzata nella
sintesi organica in virtù delle peculiari proprietà
riscontrate. Poiché i liquidi ionici sono principalmente
usati come solventi nella sintesi organica e in molte altre
applicazioni, come l’elettrodeposizione, è particolarmente
124
stable hepta-coordinated structure of the Hg2+ first
hydration shell has been observed. This result is
confirmed by the analisys of extended X-ray absorption
fine structure (EXAFS) and X-ray absorption near-edge
structure experimental data, which unambiguously show
the preference for a sevenfold instead of a sixfold
coordination..
In the last years we have synthesized a new family of 44 etriangular platinum clusters of general formula Pt3(µPBut2)3(CO)2X (X =, halide, CCR), with a limited number of
reactive sites, which proved to be useful precursors of ordered
molecular structures containing several cluster units connected
by conjugated spacers. A new member of this of this family of
cluster [Pt3(PBu2t)3I3, (1) Fig. 1], showing peculiar properties and
a different valence electrons count (42 e-), has been prepared and
characterized in the last months. As shown by electrochemical
studies, cluster 1 undergoes two reversible mono-electronic
reductions, reaching 44 e-; the salt [Pt3(PBu2t)3I3]PPN [(2), PPN
= bis-triphenylphosphinimini-um], containing the 43 e- radical
anion, has also been prepared and isolated by chemical reduction
of 1, while the 44 e- dianion is unstable and undergoes rapid
decomposition.
The structural properties of the Hg2+ hydration shells
have been investigated using radial and angular
distribution functions, while the dynamical behavior has
been discussed in terms of reorientational correlation
functions, mean residence times of water molecules in the
first and second hydration shells, and self-diffusion
coefficients. The effect of water-water interactions on the
Hg2+ hydration properties has been evaluated using the
SPC/E and TIP5P water models
1. Chillemi G., D’Angelo P., Pavel N. V., Sanna N., Barone V.;
J. Am. Chem. Soc. 2002, 124, 1968.
2. Chillemi G., Barone V., D'Angelo P., Mancini G., Persson I.,
Sanna N.; J. Phys. Chem. B. 2005, 109 , 9186.
3. G. Chillemi, G. Mancini, N. Sanna, V. Barone, S. Della
Longa, M.
Benfatto, N. V. Pavel, P. D’Angelo; J. Am. Chem. Soc. 2007,
129, 5430
Figure 1
During the first reduction the colour changes from purple
to green. All the three (neutral, mono reduced and
direduced forms) have been studied using density
functional methods. Herein we report the comparison
between computational and experimental results for all
the three different oxidation states.
1) M,. Stener, K. Albert, N. Rosch, Inorganica Chimica Acta,
1999, 286, 30-36
P 5.9
P 5.8
Ab Initio calculation and experimental
determination of 13C And 19F Chemical
Shielding Tensors of some fluorinated toluenes
dissolved in a nematic LC mixture
Alberto Marinia,b), Donata Catalanoa), Benedetta
Mennuccia), Carlo Alberto Veracinia)
a
Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via Risorgimento 35, 56126 Pisa,
Italy. [email protected]
b
Scuola Normale Superiore di Pisa, Piazza dei Cavalieri
12, 56126 Pisa, Italy.
Combined X-ray absorption spectroscopy and
Molecular Dynamics study of the Hg2+ aqua
ion.
Giordano Mancinia,b Nico Sannab, Vincenzo Baronec,
Paola D’Angeloa, Giovanni Chillemib
a
Department of Chemistry, Università di Rome “La
Sapienza”, P.le Aldo Moro 5, 00185 Roma.
[email protected]
b
CASPUR, Consorzio Applicazioni di Supercalcolo per
Università e Ricerca,Via dei Tizii 6b, 00185 Roma.
c
Dipartimento di Chimica, Università di Napoli
Federico II, Via Cintia, 80126 Napoli
In recent years, the comparison between theoretical
predictions and experimental determinations of chemical
shielding tensors has become a good test bench in
analyzing electronic structures of molecules1. In
anisotropic media the chemical shift interaction is
described by the chemical shielding tensor (σ) in an
arbitrary coordinate system. Ab initio methods give the
complete nine-elements shielding matrix for each
chemically distinguishable resonant nucleus, thus the
orientation of the principal axis system of each tensor can
be easily determined. The principal values of σ tensors
(or, at least, some components of such tensors in an
outstanding molecular frame) can also be determined by
using NMR spectroscopy of small molecules dissolved in
liquid crystals, if the molecular order parameters are
known from independent experimental data2.
Molecular Dynamics simulations of the Hg2+ ion in
aqueous solution have been carried out using an effective
two body potential. This potential is obtained from
quantum mechanical ab initio calculations in which the
many-body ion-water terms are accounted for by the
polarizable continuum method (PCM). This approach is
computationally very efficient and has allowed us to
carry out extremely long molecular dynamics
simulations, indispensable to reproduce the dynamic
properties of ionic system with a flexible first hydration
shell derived from quantum mechanical calculations. A
125
published mechanistic
experiments.
In this work we present a detailed study of the magnetic
shielding properties of some fluorotoluenes, in order (i)
to build up a shielding tensors database for fluorinated
aromatic molecules, which constitute models of the rigid
core of modern fluorinated liquid crystals3, and (ii) to
rationalize the effects of the presence of fluorine atoms
on the principal values and orientations of the 13C
chemical shielding tensors investigated.
The chemical shielding tensors have been obtained by
means of quantum-mechanical calculations, using
Gaussian’034. Geometries and carbon nuclear shielding
tensors of the different probes have been determined at
the DFT level of theory using the B3LYP/6-31G(d) and
MPW1PW91/6-311+G(d,p) combination of hybrid
functional and basis set, respectively. NMR chemical
shielding tensors have been calculated by the method of
Gauge-Including Atomic Orbitals, GIAO5. On these
model systems we have also performed an analysis in
terms of paramagnetic and diamagnetic contributions as
given by the Natural Chemical Shielding (NCS)
approach6.
13
C and 19F NMR spectra of para and meta fluorotoluene
dissolved in the nematic mixture ZLI1167, recorded at
various temperatures, have been analyzed, finally
obtaining (i) the orientational order parameters from 13C19
F dipolar couplings and (ii) some σ components from
the temperature trends of chemical shift anisotropies.
The agreement between computed and experimental
results is excellent.
hypothesis
derived
from
1. P. Cohen, Nature Reviews in drug Discovery, 1, 309-315,
2006.
P 5.11
Interpretation of CW-ESR spectroscopy of
tempo-palmitate in the 5CB liquid crystal
Antonino Polimenoa, Mirco Zerbettob, Paola Ciminob
a
Dipartimento di Scienze Chimiche, Università di
Padova, Via Marzolo 1, 35131, Padova /
[email protected]
b
Dipartimento di Chimica, Università di Napoli
“Federico II”, Complesso Universitario di Monte
Sant’Angelo Via Cintia, I-80126 Napoli
We present the interpretation of continuous wave electron
spin resonance (CW-ESR) spectra of tempo-palmitate
dissolved in the 5CB liquid crystal via our ab initio
integrated computational approach (ICA) [1]. The
methodology, already applied for the study of molecules
in isotropic media [2], is based on the stochastic
Liouville equation (SLE) approach [3,4] in which the
time evolution of the density matrix depends on the spin
Hamiltonian and on relaxing processes included as
stochastic Fokker Planck/diffusive operators. The spin
Hamiltonian is averaged over the fast vibrational motions
and the magnetic tensors (Zeeman and hyperfine) are
characterized by quantum-mechanical density functional
calculations [5,6] in both isotropic and nematic phases.
The molecule is described as a non-rigid rotator with one
internal degree of freedom which was chosen to be the
torsional angle describing the orientation of the tempo
nitroxide with respect to the alchilic chain. So, dynamic
is described by two stochastic coordinates: 1) the set of
Euler angles (Ω) giving the overall tumbling of the
molecule with respect to an inertial laboratory frame and
2) the internal angle (θ). The overall tumbling is
subjected to an external orienting potential in the nematic
phase while the internal angle θ is affected by the internal
torsional potential obtained from QM calculations.
Dynamical parameters (rotational, internal and mixed
parts of the diffusion tensor) are obtained with
calculations based on a hydrodynamic model [7]. CWESR spectra of the tempo-palmitate spin probe were
simulated in the range of temperatures from 299 K
(nematic phase) to 317 K (isotropic phase).
1. “Calculation of NMR and EPR Parameters”, eds.: Kaupp, M.;
Buhl, M.; Malkin, V. G.; WILEY-VHC Verlag GmbH & Co.
KGaA, Weinheim, 2004.
2. Fung, B. M.; Journal of Magnetic Resonance, 2005, 86, 160.
3. Kirsch, P.; Bremer, M.; Angewandte Chemie Int. Ed., 2000,
39, 4216.
4. Gaussian 03, Revision B.05. M.J. Frisch et al., Gaussian, Inc.,
Pittsburgh PA, 2003.
5. Ditchfield, R.; Molecular Physics 1974, 27, 789.
6. Bohmann, J. A.; Farrar, T. C.; and Weinhold, F.; Journal of
Chemical Physics, 1997, 107, 1173.
P 5.10
A non conventional molecular dynamics
approach for determining interactions in
MAPKs protein complexes.
M. C. Menziania, F.Filomiaa, F. De Rienzoa
University of Modena and Reggio Emilia, via Campi,
183, 41100 Modena, [email protected],
http://multiscale-school.unimore.it
a
1. Barone, V.; Polimeno, A.; Phys. Chem. Chem. Phys., 2006, 8,
4609 – 4629.
2. Polimeno, A.; Zerbetto, M.; Franco, L.; Maggini, M.; Corvaja,
C.; J. Am. Chem. Soc., 2006, 28, 4734 – 4741; Barone, V.;
Brustolon, M.; Cimino, P.; Polimeno, A.; Zerbetto, M.; Zoleo,
A.; J. Am. Chem. Soc., 2006, 128, 15865 – 15873; Zerbetto, M.;
Carlotto, S., Polimeno, A.; Corvaja, C.; Franco, L.; Toniolo, C.;
Formaggio, F.; Barone, V.; Cimino, P.; J. Phys. Chem. B., 2007,
110, 2668 – 2674.
3. Schneider, D. J.; Freed, J. H.; Adv. Chem. Phys., 1989, 73,
387 – 527.
4. Polimeno, A.; Freed, J. H.; J. Phys. Chem., 1995, 99, 10995 –
11006.
5. Neese, F.; J. Chem. Phys., 2001, 115, 11080 – 11096.
6. Ciofini, I.; Adamo, C.; Barone, V.; J. Chem. Phys., 2004, 121,
6710 – 6718.
7. Moro, G.; Chem. Phys., 1987, 118, 181 – 197.
Mitogen Activated Protein Kinase (MAPK) family has
been one of the most popular target in bio-farmacological
research in the last decade for its prominent role in a
number of diseases, including cancer, diabetes and
inflammation. In particular, the p38α subfamily is tightly
involved in proinflammatory signal transduction. A large
variety of inhibitors [1] have been designed to interfere
with signal transduction. This can be achieved by
competing with ATP or inducing conformational changes
detrimental for activation.
In this study the conformational plasticity of the
p38α activation loop has been simulated by means of
Molecular Dynamics techniques and the distribution of
dynamics states of p38α in the absence and presence of
inhibitor binding has been compared with recently
126
member was discovered and called neuroglobin (Ngb)
being predominantly expressed in the brain1. Ngb is a
single polypeptide of 151 amino acids and despite the
small sequence similarity with other globins, it displays
the typical globin fold. Oxygen, nitric oxide or carbon
monoxide can displace the distal histidine which in
ferrous Ngb (as well as ferric) is bound to the iron,
yielding a reversible adduct. Recent crystallographic data
on carboxy Ngb show that binding of an exogenous
ligand is associated to structural changes involving heme
sliding and a topological reorganization of the internal
cavities; in particular the huge internal tunnel that
connects the bulk with the active site (peculiar to Ngb) is
heavily reorganized2,3. We report the results of extended
(90 ns) molecular dynamics simulations in water of
ferrous deoxy and carboxy murine neuroglobin, which
are both coordinated on the distal site, in the latter case
by CO and in the former one by the distal His64(E7). The
long time scale of the simulations allowed us to
characterize the equilibrated protein dynamics and to
compare protein structure and dynamical behaviour
coupled to the binding of an exogenous ligand. We have
characterized the heme sliding motion, the topological
reorganization of the internal cavities, the dynamics of
the distal histidine and particularly the conformational
change of the CD loop (see figure), whose flexibility
depends ligand binding4.
P 5.12
Multivariate analysis of glass structures
obtainted by molecular dynamics simulations
M. Pota, A. Pedone, G. Malavasi, M. Cocchi, U. Segre,
M. C. Menziani
Dipartimento di Chimica, Università di Modena e Reggio
Emilia,
Via
Campi
183,
41100,
Modena.
[email protected].
Scuola di Dottorato: http://multiscale-school.unimore.it.
The correct understanding of their structure-property
relationships is required to meet predefined physical
properties of glass forming systems and ever-changing
industrial needs, but the elucidation of glass structures is
still a difficult task.
In this paper, Molecular Dynamics (MD) simulation
procedures used to produce glasses are investigated in
order to find the optimal combination of the simulation
parameters. To do this, a design of experiments (DOE)
methodology [1] has been used; the parameters of the
simulation procedure (e.g. starting relaxation temperature
and length, cooling rate and final relaxation length) and
those concerning the MD algorithm (e.g. the cut-off and
the ensemble used) have been considered as factors. The
DOE approach allows us to examine simultaneously the
influence of different simulation parameters and their
interactions and to find an approximate model that can
explain the dependencies between the response values
and the parameters considered. As the optimization
objective is to produce simulated glasses with structural
properties in good agreement with experimental results,
firstly we restrict our study to silica and 30% Na2O silica
glasses for which experimental radial distribution
function are available. Moreover, multivariate analysis is
applied to understand how structural properties described
by functions (e.g. distances and angles distribution
functions) are related with mean properties described by
single points and with the simulation parameters.
1. Burmester, T.; Weich, B.; Reinhardt, S.; Hankeln, T.; Nature,
2000, 407, 520 - 523. 2. Vallone, B.; Nienhaus, K.; Brunori, M.;
Nienhaus, G. U.; Proteins, 2004, 56, 85 - 92. 3. Vallone, B.;
Nienhaus, K.; Matthes, A.; Brunori, M.; Nienhaus, G. U.; Proc.
Natl. Acad. Sci. U.S.A., 2004, 101, 17351 - 17356. 4. Anselmi,
M.; Vallone, B.; Brunori, M.; Di Nola, A.; Biophys. J., 2007, in
press
1. Chagarov, E.; Adams, J. B.; Kieffer, J.; Modelling Simul.
Mater. Sci Eng. 2004, 12, 337-356.
P 5.14
Studio DFT della riduzione catalitica di
acetofenone
ad
1feniletanolo
mediante
[Ru(HPN)(pcym)Cl]+.
P 5.13
V.Verdolinoa, R.Cammi, P.Pelagatti, M.Balordi,
C.Pelizzi
Università degli Studi di Parma, Dip. di Chimica GIAF,
Viale G.P. Usberti 17/A, 43100 Parma
Molecular dynamics simulation of carboxy and
deoxy murine Neuroglobin
Massimiliano Anselmia, Beatrice Valloneb, Maurizio
Brunorib and Alfredo Di Nolaa
a
Dipartimento di Chimica Università di Roma La
Sapienza, P.le Aldo Moro 5, 00100 Roma,
[email protected]
b
Dipartimento di Scienze Biochimiche Università di
Roma La Sapienza, P.le Aldo Moro 5, 00100 Roma
Lo studio teorico presentato si propone di dare una
descrizione meccanicistica del trasferimento d'idrogeno
da alcol isopropilico ad acetofenone catalizzato da
[Ru(HPN)(pcym)Cl]+ (HPN = 2(difenilfosfino)anilina,
pcym= pcimene) riservando particolare interesse alla
possibile enantio selettività della reazione. Il meccanismo
è articolato in due fasi: I) formazione della specie
cataliticamente attiva (C) mediante coordinazione di
isopropossido al centro metallico (sfera interna di
coordinazione) con conseguente formazione di una specie
RuH, II) avvicinamento dell'acetofenone alla specie
idrurica mediante legame idrogeno tra l'ossigeno del
chetone e la funzione amminica del legante (sfera esterna
di coordinazione). In questa fase hanno origine gli stati di
transizione (ST1,ST2) relativi alle conformazioni proR e
S.
Gli intermedi che caratterizzano la fase I sono il
precursore catalitico [Ru(HP)(pcym)Cl2] (P), il
Globins are respiratory proteins that reversibly bind
dioxygen and other
small ligands at the
iron of a heme
prosthetic
group.
Hemoglobin
(Hb)
and myoglobin (Mb)
are
the
most
prominent members
of this protein family.
Unexpectedly a few
years ago a new
127
complesso clorodissociato [Ru(HP)(pcym)Cl]+ (PC1),
quello chelato [Ru(HPN)(pcym)Cl]+ (PC2), il complesso
Rualcossido coordinato (C) e la specie idrurica nelle due
(C1)
e
possibili
forme,
[Ru(HP)(pcym)HCl]+
+
[Ru(HPN)(pcym)H] (C2).
Da evidenze sperimentali la specie idrurica risulta essere
C2 da cui la caratterizzazione dell'intermedio Rualcolato
coordinato è stata effettuata a partire dal complesso PC2
seguendo tre possibili direzioni d'avvicinamento dello
ione ipropossido. Solo una di queste vie conduce ad un
intermedio idoneo a formare il precursore C2.
La fase II comprende lo studio degli stati di transizione
che conducono ai due alcoli enantiomeri (R) ed (S) dell'
1feniletanolo. Partendo da geometrie ottimizzate sotto
condizione di vincolo strutturale (distanza RuC
carbonilico di 4 Å) sia dei reagenti (C2+acetofenone),
che dei prodotti (residuo mettallorganico + feniletanolo),
si è effettuata una ottimizzazione dei due stati di
transizione ST1 (proS) e ST2 (proR).
E' stato inoltre verificato che entrambi gli ST ottimizzati
possiedono un solo modo vibrazionale immaginario e che
tale modo normale corrisponda alla c.r. relativa al
trasferimento sincrono di H dal metallo e di H+ dall'azoto
(fig.1).
(fig3). Anche l'analisi popolazionale ha messo in
evidenza tale interazione; i valori della carica di Mulliken
su H(44) (0.294) e su C(3) (-0.380) ben si adattano a
descrivere l'avvicinamento elettrofilo(H)-nucleofilo(C).
Ciò potrebbe essere alla base di una strategia sintetica per
favorire selettivamente la riduzione dell'enantiofaccia
proR.
Fig.3 Rappresentazione schematica dei due possibili stati
di transizione a) ST1 e b) ST2
Tutti i calcoli sono stati effettuati mediante il programma
Gaussian03[1]
al
livello
di
calcolo
DFT/B3LYP/Lanl2dz[2-4].
Tutti gli intermedi stabili sono stati ottimizzati in vuoto e
le energie valutate in single point in vuoto e simulando la
presenza del solvente (isopropanolo come ambiente di
reazione) mediante il modello PCM[5]. Gli stati di
transizione sono stati individuati al medesimo livello di
calcolo mediante ottimizzazione con metodi sincroni
(STQN) in vuoto, e determinandone il single point
introducendo il solvente.
RIFERIMENTI
[1] M. J. Frisch et al. Gaussian 03 (Gaussian, inc., Pitzburgh,
PA, '03)
[2] P. J. Hay and W. R. Wadt, J. Chem. Phys. 82, 270 (1985).
[3] W. R. Wadt and P. J. Hay, J. Chem. Phys. 82, 284 (1985).
[4] P. J. Hay and W. R. Wadt, J. Chem. Phys. 82, 299 (1985).
[5] C.Amovilli, V.Barone, R.Cammi, E.Cances, M.Cossi,
B.Mennucci, C.S.Pomelli, and J.Tomasi. In Quantum System in
Chemistry and Physics part II vol.32 of Advances in Quantum
Chemistry 227261.
Fig.1 Coordinata di reazione per gli stati di transizione ST1 ed
ST2
Fig.2 Schematizzazione del processo riduttivo
Si è quindi ottenuto il profilo completo del percorso
reattivo
(fig.2)
ottenendo
come
prodotti
[Ru(PN)(pcym)Cl] e 1feniletanolo. E' possibile quindi
effettuare alcune considerazioni di carattere strutturale ed
elettroniche in relazione agli stati di transizione ST1 e
ST2: 1) i calcoli di energia effettuati introducendo
l'effetto del solvente mostrano che ST1 ed ST2
differiscono di soli 1.5 Kcal/mol giustificando il dato
sperimentale secondo cui non vi è riscontro d'eccesso
enantiomerico, II) la configurazione proR è
energeticamente favorita nonostante sia la più ingombrata
stericamente, III) la distanza H(pcym)-C(fenile) (2.89
Ang) è paragonabile alla somma dei loro raggi di Van der
Waals (2.90 Å), presupponendo un'interazione specifica
128
INDICE COMPLESSIVO
AUTORI E COMUNICAZIONI
129
Abbotto Alessandro
P4.15, P4.16
Bee Antonio
O4.1
Acciarri M.
O4.2
Bencivenni L.
P4.6
Aggravi Marianna
P1.12
Berlier Gloria
P1.43,
Agostiano Angela
P1.9, P1.10, P1.11,
P3.9,
P4.27,
P4.34
P1.14, P2.11, P2.12,
Berti D.
O3.1
P2.13, P2.14, P3.13,
Bertinetti Luca
P4.10, P4.25
P4.18, P4.22, P4.28,
Bertolino C.A.
P4.3
P5.1
Beverina Luca
P4.15, P4.16
Alberto Gabriele
P4.25
Biancheri R.
P3.10
Albinati Alberto
O5.7, P5.7
Bianchino Erminia
P5.1
Alderighi M.
P1.13
Binetti Simona
O4.2
Alduncin Juan Antonio
O3.7
Bini M.
O4.7, P4.26
Alhaique Franco
O1.1
Biscarini F.
O4.8, P1.17
Aloisi Gian Gaetano
O4.5, P2.1, P2.2
Bisio Chiara
O4.4, P1.16, P5.4
Altamura E.
P2.13
Biosa Grazia
P1.29
Amenitsch Heinz
O3.2, P1.28
Bocchinfuso Gianfranco
O1.1, P1.38, P1.39,
Amelia Matteo
O4.5, P2.1, P2.2
Amici Augusto
O3.2, P1.28
Boccuzzi Flora
O4.6, P3.12
Andolfi Laura
O1.2
Bolis V.
P4.10
Anedda Roberto
P1.1, P4.1
Bollati Daniele
P4.25
Angelini Emma
P4.2
Bonechi Claudia
P1.12
Anselmi Massimiliano
P3.3, P5.13
Bongiorno C.
P4.5
Archetti Graziano
P4.16
Bonicelli M.G.
P3.1. P4.4
Ardu A.
P1.21
Bonino Francesca
P2.10
Arrighini G.P.
P5.2
Bordiga Silvia
O3.6
Artini C.
P4.12
Bottomley Lawrence A.
O1.3
Azzoni C.B.
O4.7
Bozio Renato
O2.3, P2.15, P4.14,
Babudri F.
O4.3
Baglioni Piero
O3.1
Brogioni B.
P1.24
Baldacchini Chiara
O1.2
Brown T.
O3.1
Baldini Chiara
P1.38
Brugger J.
P4.21
Balordi M.
P5.14
Brunori Maurizio
P5.13
Banchelli M.
O3.1
Brusatin G.
P2.15
Baratto M.C.
P1.24
Brustolon Marina
P1.7, P2.3, P2.4
Barbarossa V.
P4.6
Brutti Sergio
P4.6
Barbon Antonio
P2.4
Buzzone Samantha
O5.7, P5.2, P5.6, P5.7
Barone Guido
P1.2,
Busco C.
P4.10
P1.5, P1.6, P1.19
Bystrenova E.
O4.8, P1.17
Barone Vincenzo
P5.8
Cacace M.G.
O4.8, P1.17
Bartocci G.
P2.9
Calucci Lucia
P4.24
Bartolommei G.
O1.5, P1.20
Caminati Gabriella
O3.1
Basosi Riccardo
P1.24, P1.26
Caminati Walther
O2.4
Becucci Maurizio
I2
Caminiti Ruggero
O3.2, P1.28
P1.40
P4.15, P4.16
P1.3,
P1.4,
130
Cammi R.
P5.14
Cipolla L.
P5.3
Campo N.
P4.23
Ciriaco F.
O1.4, P5.1
Cannas C.
O3.5, P1.21
Civalleri B.
P4.9
Cannistraro Salvatore
O1.2
Cocchi M.
P5.12
Canonico Fulvio
P1.42
Cocina D.
P3.8
Capitani G.
P4.29
Collini Elisabetta
O2.3, P4.14, P4.15
Capobianco Amedeo
P1.8
Coluccia Salvatore
P1.43, P4.13, P4.20,
Caponetti Eugenio
P3.1
Capsoni D.
O4.7, P4.26
Comez L.
O2.5
Caputo G.
P4.3
Comparelli R.
P3.13, P4.11, P4.18,
Caracciolo Giulio
O3.2, P1.28
Cardini Gianni
O5.3, P2.7, P2.8
Confortin Daria
P2.3
Carlotti Benedetta
O1.3
Convertino Anna Lisa
P4.8
Carnasciali M.M.
P4.12
Coppola Teresa
P1.30
Carullo P.
P1.6
Corcelli Angela
P1.10, P1.11
Caruso Tonino
P1.8
Corda Marcella
P1.1
Cascio C.
P4.5
Cormack Alastair N.
O5.8
Caselli M.
P1.27, P3.13
Corno Marta
P4.9, P4.10
Castagnolo M.
P1.14
Corriceli Michele
P4.11
Castellano C.
P4.17
Cosentino Ugo
P5.3
Casu Mariano
P1.1, P4.1
Cosma P.
P1.9, P1.14, P4.22
Catalano Donata
P5.9
Cossi M.
P1.16, P5.4
Catti Michele
P4.7
Costa Giorgio A.
P4.12
Catucci Lucia
P1.9, P1.10, P1.11,
Costi M.P.
P1.27
P1.14
Coviello Tommasina
O1.1
Causà Mauro
P1.35
Cozzoli P.D.
P4.29
Ceccarelli Matteo
P1.1
Crescenzi Orlando
O2.1
Ceccaroni G.
P4.4
Curri Maria Lucia
O3.7,
Ceraulo L.
P3.10
P4.11, P4.18, P4.21,
Ceschino Raffaella
P4.25
P4.22, P4.28, P4.29,
Chianese Elena
P1.2,
P4.27, P4.34
P1.3,
P4.28
P1.4,
P3.13,
P5.1
P1.5
Czub Joanna
O3.4
Chiappe C.
P5.6
Dąbrowski Roman
O3.4
Chiarello Gian Luca
P4.32
D’Agostino R.
P4.2
Chidichimo Giuseppe
O2.2
D’Alessio Giuseppe
P1.41
Chillemi Giovanni
P5.8
Damin Alessandro
P1.42, P2.10
Chillura Martino Delia
P3.2
D’Amore Maddalena
P5.4
Chiodelli G.
P4.19
D’Angelo Paola
P5.8
Chiorino Anna
O4.6, P3.12
Davit D.
P4.27
Ciaffoni Luca
P4.15
De Benedetto Giuseppe
P2.5
Cimberle M.R.
P4.17
De Filpo Giovanni
O2.2
Cimino Paola
O2.1, P5.11
De Leo Vincenzo
P1.10
Ciorba S.
P2.9
De Lisi R.
O3.3, P3.6
131
P4.8,
Del Sole Roberta
P2.6
Fini P.
P1.9, P1.14, P4.22
De Luca Agnese
P2.6
Fiorani D.
O3.5
Del Vecchio P.
P1.6
Fiore P. Nicoletta
O2.2
De Maria G.
P4.6
Fioretto D.
O2.5
De Nicolò Nicola
P2.11, P2.14
Fittipaldi Maria
P4.18
Depalo N.
P4.11
Flor Giorgio
P4.19
De Rienzo F.
P5.10
Fois Ettore
O5.1
D’Errico Gerardino
P3.4, P3.7
Formaggio Fernando
P1.38, P1.39, P1.40
De Santis Pasquale
O1.7, P1.30, P1.33
Forni Lucio
P4.32
P1.33
Fortunati Ilaria
P2.15, P4.15, P4.16
Di Mauro A.E.
P1.14
Forzatti P.
P1.44
Di Nola Alfredo
P3.3, P5.13
Franco Lorenzo
P2.3
Dionigi C.
O4.8, P1.17
Franza A.S.
P4.28
Di Pietro Elisa
O5.3
Frielinghaus Henrich
P3.4
Diré S.
P2.15
Frola F.
P1.44
Diso Daniela
P4.28
Galantini Luciano
P1.18, P3.3
Di Vita Edoardo
O1.8
Galinetto P.
O4.7
Donati Alessandro
P1.12
Gallina M.E.
O2.5
Duce Celia
P1.13
Gamba A.
O5.1
Dutta S.
O4.8, P1.17
Gambinossi F.
O3.1
Elisei Fausto
O1.3, O4.5, P2.1,
Garbin Eleonora
P4.14
P2.2
Gatteschi D.
P1.21, P4.18
Enzo Stefano
P3.2
Gatti G.
P4.34
Epis Thomas
P1.31
Gatto Emanuela
P1.38, P1.39, P1.40
Era Benedetta
P1.1
Gauss Jürgen
O5.2
Fabio M.
P1.23
Gauzzi F.
P4.4
Fabrizi de Briani Fabrizia
O5.7, P5.7
Genga Alessandra
P1.15
Faga M.G.
P4.13
Genoni Alessandro
P5.5
Fais Antonella
P1.1
Geppi Marco
O3.4, P4.24
Fakhfouri V.
P4.21
Ghezzi Sergio
P4.16
Famà L.
P1.15
Ghigo Giovanni
P1.35
Fanara S.
P3.10
Ghiotti G.
P1.44, P4.26
Fanigliulo Ameriga
P2.5
Ghitti Michela
P5.5
Faralli Cristian
P2.7, P2.8
Giamello E.
P4.26
Farinola Gianluca
O4.3
Giancane Gabriele
O4.3, P4.22
Favero Laura
O2.4
Giancola Concetta
P1.19, P1.22
Feix Jimmy B.
P1.25
Giannici F.
P4.29
Ferrante Camilla
O2.3, P4.14, P4.15,
Gianotti Enrica
P4.3, P4.20, P4.27
P4.16
Giansanti L.
P3.1
Ferrari Stefania
P1.27
Giardina P.
P1.24
Ferretti Maurizio
P4.17
Ginocchietti G.
P2.9
Filippo Emanuela
P3.5
Giordana Anna
P1.35
Filomia F.
P5.10
Giordano C.
P3.10
132
Giorgianni Santi
O2.7, P4.31
Libal J.
O4.2
Giotta Livia
P2.12, P2.13, P2.14
Licciulli Antonio
P4.28
Giuliano Barbara Michela O2.4
Lietti L.
P1.44
Gozzo F.
P4.19
Lippolis V.
P1.9
Gradzielski M.
O3.3, P3.6
Locatelli Danika
P4.16
Grassi N.
P4.18
Lorenzo Franco
P2.3
Grassini S.
P4.2
Lorusso Antonella
P4.23, P4.33
Greco P.
O4.8, P1.17
Lovergine Nicola
P4.33
Gregori M.
P5.3
Macedo T.R.
P1.16
Gruetzner G.
P4.21
Madarasz E.
O4.8
Guglielmi M.
P2.15
Malavasi Gianluca
P4.19, P5.12
Guidotti Carla
O5.7, P5.2, P5.7
Malavasi L.
O5.8
Guldi Dirk M.
I4
Malvaldi Marco
P5.6
Hahm K.S.
P1.40
Manca Gabriele
O5.7, P5.7
Hauser Marcus
P1.29
Mancini Giordano
P3.1, P5.8
Hud Nicholas V.
O1.3
Manco G.
P1.6
Huskens J.
P4.11
Mangiapia Gaetano
P3.4, P3.7
Ibba Giulio
P3.2
Mangone A.
P1.15
Idakiev Vasko
P3.12
Manno Daniela
P1.15, P3.5
Ielpo Piera
P3.13
Manyar Haresh G.
P4.20
Iliade P.
O4.3
Manzoli Maela
O4.6, P3.12
Improta Roberto
O5.6
Maranzana A.
P1.35
Indelli G.F.
P4.5
Marchese Leonardo
O4.4, P1.16, P1.43,
Ingrosso Chiara
P4.21, P4.22
Iozzi M.F.
P1.16
Marchetti Lorella
O5.7, P5.7
Italiano Francesca
P2.12
Marchettini Nadia
P1.12, P1.34
Jelitai M.
O4.8
Marchini Cristina
O3.2, P1.28
Jover Aida
P3.3
Margarone D.
P4.23
Kahr Bart
P2.4
Mariano G.
P4.4
Kehagias Nikolaos
O3.7
Marini Alberto
O3.4, P4.24, P5.9
Kuczyński Wojciech
O3.4
Maris Assimo
O2.4
Laganara C.
P1.15
Marletta Giovanni
O1.1, O1.6, P4.30
Lamanna Ugo Tommaso
O1.4, P5.2
Maróti Péter
P2.11, P2.13, P2.14
Lamberti Carlo
P1.42, P3.9
Martinelli A.
P4.17
Lasorella G.
P3.13
Martini C.
O4.8
Latterini Loredana
O1.3, O4.5, P2.1,
Martino Luigi
P1.19
P2.2
Martra Gianmario
P4.10, P4.13, P4.25
Lazar A.N.
O4.8, P1.17
Mascolo Giuseppe
P1.11, P4.28
Lazzara G.
O3.3, P3.6
Masini R.
P4.12, P4.17
Lazzoi M.R.
P2.6
Massarotti Vincenzo
O4.7, P4.26
Leggio Claudia
P1.18, P3.3
Mastrogiacomo Disma
P2.12
Leo Gabriella
P4.8
Mattia Carlo A.
P1.22
Leoni Piero
O5.7, P5.7
Maurino V.
P4.13
P4.34, P5.4
133
Mavelli F.
O1.4, P5.1
Nicotra F.
P5.3
Mayol Luciano
P1.30
Norden B.
O3.1
Mazzarella Lelio
P1.41
Nova I.
P1.44
Mazzuca Claudia
O1.1, P1.40
Olivucci Massimo
P1.26
Mazzucato Simone
P4.16
Omar Hassan O.
O4.3
Mazzucato Ugo
P2.9
Ortona Ornella
P3.4, P3.7
Mecerreyes David
O3.7
Paduano Luigi
P3.4, P3.7
Meijide Francisco
P3.3
Pagani Giorgio A.
P4.15
Melandri Sonia
O2.4
Paganini M.C.
P4.26
Menegazzo Federica
O4.6
Pagano Bruno
P1.19, P1.22
Mennucci Benedetta
P5.9
Pagliai Marco
P2.7, P2.8
Menziani Maria Cristina
O5.8, P4.9, P5.10,
Paladini F.
P4.23
P5.12
Palleschi Antonio
O1.1, P1.38, P1.39,
Merlino Antonello
P1.41
Merone L.
P1.6
Palmisano F.
O4.3
Messina Grazia M.L.
O1.6, P4.30
Palumbo F.
P4.2
Metzroth Thorsten
O5.2
Panniello Anna Maria
P3.13, P4.28
Michetti Emanuela
P1.30
Paolantoni M.
O2.5, P2.8
Milano Francesco
P1.10, P2.11, P2.12,
Parkinson Gary N.
P1.22
P2.13, P2.14
Pascale F.
P3.1
Milioto S.
O3.3, P3.6
Pascale M.
P1.9
Minella M.
P4.13
Pastore Heloise O.
O4.4, P1.43
Minero C.
P4.13
Pavel Nicolae Viorel
P1.18, P3.3
Mohapatra Swagat K.
P5.7
Pavone Michele
O2.1, O5.5
Monaco Guglielmo
O5.4
Peddis Davide
O3.5, P1.21
Moncelli M. R.
O1.5, P1.20
Pedone Alfonso
O5.8, P4.9, P5.12
Montani Maura
O3.2, P1.28
Pedron Danilo
P4.16
Monti S.
P1.13
Pelagatti P.
P5.14
Morandi Sara
P4.26
Pelizzetti Ezio
P4.13
Moro Giorgio
P5.3
Pelizzi C.
P5.14
Morosetti S.
O1.7, P1.33
Peluso Andrea
P1.8
Morresi Assunta
O2.5, P2.8
Perticaroli S.
P2.8
Mørup S.
O3.5
Petraccone Luigi
P1.19
Moudrakovski Igor L.
P4.1
Piccaluga G.
O3.5, P1.21
Mozzati M.C.
O4.7
Pieraccini Stefano
P5.5
Muratore N.
O3.3, P3.6
Pignataro Bruno
P4.5
Murugesan V.
P4.27
Pindinelli Emanuela
P1.23
Musinu Anna
O3.5, P1.21
Pinna Francesco
O4.6
Musumeci C.
P4.5
Piotto S.
P5.1
Nagy László
P2.11, P2.13, P2.14
Pirone R.
P1.43
Narducci Dario
O1.8
Pironti Giuseppina
P1.4
Naso Francesco
O4.3
Pisano Sabrina
P1.30
Nassisi Vincenzo
P4.23, P4.33
Pispisa Basilio
P1.38, P1.40
P1.40
134
Pistolesi Sara
P1.25, P1.26
Ruzzi Marco
P2.3
Pitea Demetrio
P5.3
Saadhu V.
P4.11
Pizzo Elio
P1.41
Saladino Maria Luisa
P3.2
Placido Tiziana
P4.29
Sangregorio C.
P1.21, P4.18
Pogni Rebecca
P1.24, P1.25, P1.26
Sanna Nico
P5.9
Polimeno Antonino
P5.11
Sannia G
P1.24
Pomposo Josè Adolfo
O3.7
Santai Catherine T.
O1.3
Ponterini Glauco
P1.27
Santoro Fabrizio
O5.6
Portman Jenni
O1.8
Saracino G.A.A.
P5.3
Pota Marco
P5.12
Sartorio Roberto
P3.4
Pozzi Daniela
O3.2, P1.28
Sassi P.
O2.5, P2.8
Prete Paola
P4.33
Satriano Cristina
O1.6, P4.30
Prevost S.
O3.3
Savino Maria
P1.30
Prinetto F.
P1.44
Scandurra A.
P4.5
Puzzarini Cristina
O5.2
Scarano D.
P1.42
Randazzo Antonio
P1.22
Scaranto Jessica
O2.7, P4.31
Ravesi S.
P4.5
Scarpa A.
P1.43
Rebaud Vincent
O3.7
Scarponi F.
O2.5
Rega Nadia
I5
Schettino Vincenzo
O5.3, P2.7, P2.8
Ricchiardi Gabriele
O3.6, P1.42, P3.8,
Schiraldi Alberto
P1.31, P1.32
P3.9
Sciancalepore C.
P4.8, P5.1
Riccio Alessia
P1.3
Scipioni Anita
O1.7, P1.33
Riccio Angelo
P1.2,
Scolaro Sara
P4.16
P1.5
Segre Ulderico
O5.8, P5.12
Rich P.
I1
Selli Elena
O2.6, P4.32
Righetto Stefania
P4.16
Serra Antonio
P3.5
Ripmeester John A.
P4.1
Siciliano M.
P1.15
Ristori Sandra
P1.29
Siciliano Tiziana
P1.15, P3.5
Rivallan Mickaël
P3.9
Signorini Raffaella
P2.15, P4.16
Roberto Dominique
P4.16
Simoncini Eugenio
P1.29, P1.34
Rochira S.
P1.14
Sinicropi A.
P1.24, P1.26
Rosalbino F.
P4.2
Sironi Maurizio
P5.5
Rossetti Ilenia
P4.32
Söderman Olle
P3.11
Rossi Claudio
P1.12
Solaro R.
P1.13
Rossi F.
P1.34
Soldatov Dmitriy V.
P4.1
Rossi M.
P1.6
Sotomayor Torres C. M.
O3.7
Rossi V.
P1.37
Soto Tellini Victor Hugo
P3.3
Ruggerone Paolo
P1.1
Spalletti Anna
P2.9
Ruggirello A.
P3.10
Spoto Giuseppe
O3.6, P2.10, P3.8
Ruiz Eliseo
P5.6
Stella Lorenzo
P1.38, P1.39, P1.40
Ruiz-Mirazo K.
O1.4
Stoliar P.
O4.8, P1.17
Ruocco Giancarlo
I3
Strass M.
P1.43
Rustici Mauro
P1.29, P1.34
P1.3,
P1.4,
135
Striccoli Marinella
O3.7, P3.13, P4.8,
Velardi Luciano
P4.23, P4.33
P4.11, P4.18, P4.21,
Velino Biagio
O2.4
P4.28, P4.29, P5.1
Veloso Martins Gesley A. P1.43, P4.34
Superti Guilherme
O4.4
Venanzi Mariano
P1.38, P1.39, P1.40
Tabacchi Gloria
O5.1
Ventrella Andrea
P1.11
Tabakova Tatyana
P3.12
Veracini Carlo Alberto
O3.4, P4.24, P5.9
Tadini-Buoninsegni F.
O1.5, P1.20
Verdolino Vincenzo
P5.14
Talarico G.
P5.4
Vergara Alessandro
P1.41
Tamborra Michela
O3.7, P4.8
Verrone R.
P1.9
Tanese Cristina
O4.3
Villa A.
P5.3
Tealdi C.
P4.19
Vindigni Floriana
O4.6, P3.12
Tepore Antonio
P3.5
Vishnuvarthan Muthusami P4.27
Terasaki Osamu
P4.20
Vitillo Jenny G.
O3.6, P2.10, P3.8
Tiezzi Enzo
P1.12, P1.29
Voigt A.
P4.21
Tiné M.R.
P1.13
von Corswant Christian
P3.11
Tomassetti M.
P1.37
Wustholz Kristin L.
P2.4
Tonachini Glauco
P1.35
Zambonin Pier Giorgio
O4.3
Tonazzini I.
O4.8
Zanasi Riccardo
O5.4
Toniolo Claudio
P1.38, P1.39, P1.40
Zanello Piero
O5.7, P5.7
Torrisi L.
P4.23
Zanré Roberto
P2.4
Torsi Luisa
O4.3
Zavorotynska Olena
P2.10
Traini A.
P1.15
Zecchina Adriano
O3.6, P1.42, P2.10,
Traversa M.
P4.33
Trevisan Valentina
O4.6
Zerbetto Michele
P4.16
Troisi Luigino
P1.23
Zerbetto Mirco
P5.11
Trotta Massimo
P2.11, P2.12, P2.13,
Zoleo Alfonso
P1.7, P2.3
P3.8, P3.9
P2.14
Tumbiolo Simonetta
P4.20
Turchetti G.
O1.7
Turco Liveri Vincenzo
P3.10
Ubaldini A.
P4.12
Ugliengo P.
P4.9, P4.10
Ugo Renato
P4.16
Urban Stanisław
O3.4
Usseglio Sergio
P1.42
Vaccaro Mauro
P3.11
Valli Ludovico
O4.3, P4.22
Vallone Beatrice
P5.13
Vanoni Maria A.
O5.1
Varra Michela
P1.30
Vasapollo Giuseppe
P2.6
Vázquez Tato José
P3.3
Vecchio Stefano
P1.36, P1.37
136
ELENCO DELEGATI
137
Aggravi
Marianna
Università di Siena
[email protected]
Agostiano
Angela
Università di Bari
[email protected]
[email protected]
Amelia
Matteo
Università degli Studi di Perugia
Anedda
Roberto
Università di Cagliari
[email protected]
Angelini
Emma
Politecnico di Torino
[email protected]
Anselmi
Massimiliano
Università di Roma "La Sapienza"
[email protected]
Baglioni
Piero
Università di Firenze e CGSI
[email protected]; [email protected]
Balucani
Nadia
Università degli Studi di Perugia
[email protected]
Barone
Guido
Università di Napoli Federico II
[email protected]
Barone
Vincenzo
Università di Napoli "Federico II"
[email protected]
Basosi
Riccardo
Università di Siena
[email protected]
Becucci
Maurizio
Università di Firenze
[email protected]
Bee
Antonio
Costruzioni Solari srl
[email protected]
Bennici
Simona
Università degli Studi di Milano
[email protected]
Bertolino
Chiara Alessandra
Università degli Studi di Torino
[email protected]
Bianchino
Erminia
Università di Bari
[email protected]
Binetti
Simona
Università di Milano Bicocca
[email protected]
Bisio
Chiara
Università del Piemonte Orientale "A. Avogadro"
[email protected]
Bocchinfuso
Gianfranco
Università di Roma "Tor Vergata"
[email protected]
Bonicelli
Maria Grazia
Università di Roma "La Sapienza"
[email protected]
Bozio
Renato
Università di Padova
[email protected]
Brustolon
Marina
Università degli Studi di Padova
[email protected]
Brutti
Sergio
Università di Roma "La Sapienza"
[email protected]
Bruzzone
Samantha
Università di Pisa
[email protected]
Bystrenova
Eva
Institute for Nanostructured Materials Studies
[email protected]
Caminati
Gabriella
Università di Firenze
[email protected]
Caminiti
Ruggero
Università di Roma "La Sapienza"
[email protected]
Cannistraro
Salvatore
Università della Tuscia
[email protected]
Capobianco
Amedeo
Università di Salerno
[email protected]
Caponetti
Eugenio
Università di Palermo
[email protected]
Caracciolo
Giulio
Università di Roma "La Sapienza"
[email protected]
Carlotti
Benedetta
Università degli Studi di Perugia
[email protected]
Carnasciali
M. Maddalena
Università degli Studi di Genova
[email protected]
Casarin
Maurizio
Università degli Studi di Padova
[email protected]; [email protected]
Casu
Mariano
Università di Cagliari
[email protected]
Catti
Michele
Università di Milano Bicocca
[email protected]
Catucci
Lucia
Università di Bari
[email protected]
Ceccarelli
Raffaella
Politecnico di Torino
[email protected]
Chidichimo
Giuseppe
Università della Calabria
[email protected]
Chiorino
Anna
Università degli Studi di Torino
[email protected]
Cimino
Paola
Università degli Studi di Salerno
[email protected]
Coluccia
Salvatore
Università di Torino
[email protected]
Comparelli
Davide
Università di Bari
[email protected]
Convertino
Annalisa
Istituto per lo Studio dei Materiali Nanostrutturati
[email protected]
Corno
Marta
Università di Torino
[email protected]
Corricelli
Michela
IPCF-CNR Bari
[email protected]
Cosentino
Ugo
Università degli Studi di Milano Bicocca
[email protected]
Cosma
Pynalisa
Università di Bari, CNR-IPCF
[email protected]
Costa
Giorgio Andrea
Università di Genova
[email protected]
Croce
Fausto
Università degli Studi "G. D'Annunzio"
[email protected]
138
Curri
M. Lucia
CNR-IPCF
Bari
[email protected]
D'Amore
Maddalena
Università Piemonte Orientale
[email protected]
De Benedetto
Giuseppe
Università del Salento
[email protected]
De Filpo
Giovanni
Università della Calabria
[email protected]
De Nicolò
Nicola
IPCF-CNR
[email protected]
Bari
De Palo
Nicoletta
Università di Bari
[email protected]
De Santis
Pasquale
Università di Roma "La Sapienza"
[email protected]
Del Sole
Roberta
Università del Salento
[email protected]
Di Pietro
Elisa
Università degli Studi di Firenze
[email protected]
Dimo
Luigi
Università del Salento
[email protected]
Donati
Alessandro
Università di Siena
[email protected]
Duce
Celia
Università di Pisa
[email protected]
Elisei
Fausto
Università degli Studi di Perugia
[email protected]
Fabrizi de Biani
Fabrizia
Università di Siena
[email protected]
Faga
Maria Giulia
Università di Torino
[email protected]
Faralli
Cristian
Università di Firenze
[email protected]
Ferrante
Camilla
Università di Padova
[email protected]
Ferretti
Maurizio
Università degli Studi di Genova
[email protected]
[email protected]
Fini
Paola
IPCF-CNR
Fittipaldi
Maria
INSTM
[email protected]
Flor
Giorgio
Università degli Studi di Pavia
[email protected]
Fortunati
Ilaria
Università degli Studi di Padova
[email protected]
Frola
Francesca
Università di Torino
[email protected]
Galantini
Luciano
Università di Roma "La Sapienza"
[email protected]
Garbin
Eleonora
INSTM
[email protected]
Genga
Alessandra
Università del Salento
Ghiotti
Giovanna
Università di Torino
[email protected]
Ghitti
Michela
Università degli Studi di Milano
[email protected]
Giancane
Gabriele
Università del Salento
[email protected]
Giancola
Tina
Università di Napoli Federico II
[email protected]
Giotta
Livia
Università del Salento
[email protected]
Gatti
Bari
Università del Piemonte Orientale
[email protected]
Girlando
Alberto
Università di Parma
[email protected]
Guldi
Dirk M.
Friedrich-Alexander-Universität Erlangen-Nürnberg
[email protected]
Ielpo
Piera
Università di Bari
[email protected]
Ingrosso
Chiara
Università di Bari
[email protected]
[email protected]
Iozzi
Maria Francesca
Univ. Piemonte Orientale “Amedeo Avogadro”
Italiano
Francesca
IPCF-CNR Bari
Lamanna
Ugo
Università di Bari
[email protected]
Latterini
Loredana
Università degi Studi di Perugia
[email protected]
Lazar
Adina
Istituto Studio dei Materiali Nanostrutturati
[email protected]
Lazzara
Giuseppe
Università degli Studi di Palermo
[email protected]
Leggio
Claudia
Università di Roma "La Sapienza"
[email protected]
Lo Russo
Antonella
Università del Salento
[email protected]
Malvaldi
Marco
Università di Pisa
[email protected]
Manca
Gabriele
Università di Pisa
[email protected]
Mancini
Giordano
Università di Roma "La Sapienza" - CASPUR
[email protected]
Mangiapia
Gaetano
Università degli Studi di Napoli "Federico II"
[email protected]
Manno
Daniela
Università del Salento
[email protected]
Manyar
Haresh
Università degli Studi di Torino
[email protected]
Manzoli
Maela
Università degli Studi di Torino
[email protected]
Marchese
Leonardo
Università degli Studi del Piemonte Orientale
[email protected]
Marchettini
Nadia
Università di Siena
[email protected]
139
Marini
Alberto
Scuola Normale Superiore
[email protected]; [email protected]
Marletta
Giovanni
Università degli Studi di Catania
[email protected]
Martino
Luigi
Università di Napoli Federico II
[email protected]
Martra
Gianmario
Università di Torino
[email protected]
Masia
Marco
Università degli Studi di Sassari
[email protected]
Massarotti
Vincenzo
Università di Pavia
[email protected]
Mavelli
Fabio
Università di Bari
[email protected]
Mazzucato
Ugo
Università di Perugina
[email protected]
Melandri
Sonia
Università di Bologna
[email protected]
Menziani
Maria Cristina
Università di Modena e Reggio Emilia
[email protected]
Milano
Francesco
IPCF-CNR
Milioto
Stefania
Università di Palermo
Monaco
Guglielmo
Università degli Studi di Salerno
[email protected]
Moncelli
Maria Rosa
Università degli Studi di Firenze
[email protected]
Morandi
Sara
Università di Torino
[email protected]
Moro
Giorgio
Università di Padova
[email protected]
Morresi
Assuntina
Università di Perugina
[email protected]
Muratore
Nicola
Università di Palermo
[email protected]
Bari
[email protected]
[email protected]
Musinu
Anna
Università di Cagliari
[email protected]
Muthusamy
Vishnuvarthan
Università degli Studi di Torino
[email protected]
Narducci
Dario
Università di Milano Bicocca
[email protected]
Ortona
Ornella
Università di Napoli "Federico II"
[email protected]
Paduano
Luigi
Università di Napoli "Federico II"
[email protected]; [email protected]
Pagano
Bruno
Università degli Studi di Salerno
[email protected]
Palumbo
Luisa
Università di Torino
[email protected]
Panniello
Anna Maria
Università degli Studi di Bari
[email protected]
Pavel
Nicolae Viorel
Università di Roma "La Sapienza"
[email protected]
Pavone
Michele
Università degli Studi di Napoli "Federico II"
[email protected]
Peddis
Davide
Ass. Univ. del Sulcis Iglesiente (A.U.S.I.)
[email protected]
Pedone
Alfonso
Università di Modena e Reggio Emilia
[email protected]
Piccaluga
Giorgio
Università di Cagliari
[email protected]
Pierri
Paolo
Centro Studi e Ricerche di Sanità Militare
[email protected]
Pignataro
Bruno
Università di Palermo
[email protected]
Pignataro
Salvatore
Università di Catania
[email protected]
Pindinelli
Emanuela
Università del Salento
[email protected]
Pitea
Demetrio
Università degli Studi di Milano-Bicocca
[email protected]
Placido
Tiziana
IPCF-CNR
[email protected]
Pogni
Rebecca
Università di Siena
[email protected]
Polimeno
Antonino
Università di Padova
[email protected]
Ponterini
Glauco
Università di Modena e Reggio Emilia
[email protected]
Pota
Marco
Università di Modena e Reggio Emilia
[email protected]
Pozzi
Daniela
Università di Roma "La Sapienza"
[email protected]
Puzzarini
Cristina
Università di Bologna
[email protected]
Rega
Nadia
Università di Napoli Federico II
[email protected]
Ricchiardi
Gabriele
Università di Torino
[email protected]
Rich
Peter
University College, London
[email protected]
Ruocco
Giancarlo
Università di Roma "La Sapienza"
[email protected]
Russo
Nino
Università della Calabria
[email protected]
Rustici
Mauro
Università di Sassari
[email protected]
Sansone
Alberto
Santoro
Fabrizio
Molecular Modelling Lab
[email protected]
[email protected]
Satriano
Cristina
Università degli Studi di Catania
[email protected]
Savino
Maria
Università di Roma "La Sapienza"
[email protected]
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Scaranto
Jessica
Università Ca' Foscari di Venezia
[email protected]
Schettino
Vincenzo
Università di Firenze
[email protected]
Schiraldi
Alberto
Università degli Studi di Milano
[email protected]
Scipioni
Anita
Università di Roma "La Sapienza"
[email protected]
Segre
Ulderico
Università di Modena e Reggio Emilia
[email protected]
Selli
Elena
Università degli Studi di Milano
[email protected]
Simoncini
Eugenio
Università degli Studi di Siena
[email protected]
Spalletti
Anna
Università degli Studi di Perugia
[email protected]
Striccoli
Marinella
CNR-IPCF Division of Bari
[email protected]
Suffritti
Giuseppe Baldovino
Università di Sassari
[email protected]
Tabacchi
Gloria
Università dell'Insubria
[email protected]
Tiezzi
Enzo
Università di Siena
[email protected]
Tiné
Maria Rosaria
Università di PIsa
[email protected]
Tomasi
Iacopo
Università di Pisa
[email protected]
Tonachini
Glauco
Università degli Studi di Torino
[email protected]
Torsi
Luisa
Università di Bari
[email protected]
Trotta
Massimo
CNR-IPCF BARI
[email protected]
Turco Liveri
Vincenzo
Università degli Studi di Palermo
[email protected]
Vaccaro
Mauro
Università di Napoli Federico II
[email protected]
Valli
Ludovico
Università del Salento
[email protected]
Vecchio
Stefano
Università di Roma "La Sapienza"
[email protected]
Velardi
Luciano
Università del Salento
[email protected]
Velino
Biagio
Università di Bologna
[email protected]
Veloso Martins
Gesley Alex
Università degli Studi di Torino
[email protected]
Venanzi
Mariano
Università di Tor Vergata
[email protected]
Verdolino
Vincenzo
Università degli Studi di Parma
[email protected]
Vergara
Alessandro
Università di Napoli Federico II
[email protected]
Verrone
Raffaella
Università degli Studi di Bari
[email protected]
Vindigni
Floriana
Università di Torino
[email protected]
Vittucci
Vito
Centro Studi e Ricerche di Sanità Militare
[email protected]
Zavorotynska
Olena
Università di Torino
[email protected]
Zerbetto
Mirco
Università di Padova
[email protected]
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